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Herbert JM, Jacobson LD. Nature's most squishy ion: The important role of solvent polarization in the description of the hydrated electron. INT REV PHYS CHEM 2011. [DOI: 10.1080/0144235x.2010.535342] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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52
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Nelson TR, Chaban VV, Prezhdo VV, Prezhdo OV. Vibrational Energy Transfer between Carbon Nanotubes and Nonaqueous Solvents: A Molecular Dynamics Study. J Phys Chem B 2010; 115:5260-7. [DOI: 10.1021/jp108776q] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tammie R. Nelson
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Vitaly V. Chaban
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Victor V. Prezhdo
- Institute of Chemistry, Jan Kochanowski University, 25-406 Kielce, Poland
| | - Oleg V. Prezhdo
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
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53
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Jacobson LD, Herbert JM. A one-electron model for the aqueous electron that includes many-body electron-water polarization: Bulk equilibrium structure, vertical electron binding energy, and optical absorption spectrum. J Chem Phys 2010; 133:154506. [DOI: 10.1063/1.3490479] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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54
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Tachikawa H. Electron Capture Dynamics of a Water Molecule Connected to a Cyclic Water Trimer: A Direct Ab Initio MD Approach. J Phys Chem A 2010; 114:10309-14. [DOI: 10.1021/jp105731u] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Hiroto Tachikawa
- Division of Materials Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan
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55
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Affiliation(s)
- Ross E Larsen
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095-1569, USA.
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56
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Mones L, Turi L. A new electron-methanol molecule pseudopotential and its application for the solvated electron in methanol. J Chem Phys 2010; 132:154507. [DOI: 10.1063/1.3385798] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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57
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Menzeleev AR, Miller TF. Ring polymer molecular dynamics beyond the linear response regime: Excess electron injection and trapping in liquids. J Chem Phys 2010; 132:034106. [DOI: 10.1063/1.3292576] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
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58
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Yagasaki T, Ono J, Saito S. Ultrafast energy relaxation and anisotropy decay of the librational motion in liquid water: A molecular dynamics study. J Chem Phys 2009; 131:164511. [DOI: 10.1063/1.3254518] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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60
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Coridan RH, Schmidt NW, Lai GH, Wong GCL. Hydration structures near finite-sized nanoscopic objects reconstructed using inelastic x-ray scattering measurements. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:424115. [PMID: 21715850 DOI: 10.1088/0953-8984/21/42/424115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Recent work has shown that it is possible to use high resolution dynamical structure factor S(q,ω) data measured with inelastic x-ray scattering to reconstruct the Green's function of water, which describes its dynamical density response to a point charge. Here, we generalize this approach and describe a strategy for reconstructing hydration behavior near simple charge distributions with excluded volumes, with the long term goal of engaging hydration processes in complex molecular systems. We use this Green's function based imaging of dynamics method to generate hydration structures and show that they are consistent with those of well-studied model systems.
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Affiliation(s)
- Robert H Coridan
- Department of Physics, University of Illinois at Urbana-Champaign, IL 61801, USA
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61
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Jacobson LD, Williams CF, Herbert JM. The static-exchange electron-water pseudopotential, in conjunction with a polarizable water model: A new Hamiltonian for hydrated-electron simulations. J Chem Phys 2009; 130:124115. [DOI: 10.1063/1.3089425] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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62
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Griffin GB, Young RM, Ehrler OT, Neumark DM. Electronic relaxation dynamics in large anionic water clusters: (H[sub 2]O)[sub n]−] and (D[sub 2]O)[sub n]−] (n=25–200). J Chem Phys 2009; 131:194302. [DOI: 10.1063/1.3263419] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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63
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Lindner J, Unterreiner AN, Vöhringer P. Femtosecond spectroscopy of solvated electrons from sodium-ammonia-d3 solutions: Temperature jump versus local density jump. J Chem Phys 2008; 129:064514. [DOI: 10.1063/1.2965818] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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65
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Pratihar S, Chandra A. Microscopic solvation of a lithium atom in water-ammonia mixed clusters: Solvent coordination and electron localization in presence of a counterion. J Chem Phys 2008; 129:024511. [DOI: 10.1063/1.2951989] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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66
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Zhang L, Yan S, Cukier RI, Bu Y. Solvation of Excess Electrons in LiF Ionic Pair Matrix: Evidence for a Solvated Dielectron from Ab Initio Molecular Dynamics Simulations and Calculations. J Phys Chem B 2008; 112:3767-72. [DOI: 10.1021/jp800381a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Liang Zhang
- Key Laboratory for Colloid and Interface Chemistry of Ministry of Education, The Modeling & Simulation Chemistry Division, School of Chemistry & Chemical Engineering, Shandong University, Jinan, 250100, P. R. China, and Department of Chemistry, Michigan State University, East Lansing, Michigan 48824
| | - Shihai Yan
- Key Laboratory for Colloid and Interface Chemistry of Ministry of Education, The Modeling & Simulation Chemistry Division, School of Chemistry & Chemical Engineering, Shandong University, Jinan, 250100, P. R. China, and Department of Chemistry, Michigan State University, East Lansing, Michigan 48824
| | - R. I. Cukier
- Key Laboratory for Colloid and Interface Chemistry of Ministry of Education, The Modeling & Simulation Chemistry Division, School of Chemistry & Chemical Engineering, Shandong University, Jinan, 250100, P. R. China, and Department of Chemistry, Michigan State University, East Lansing, Michigan 48824
| | - Yuxiang Bu
- Key Laboratory for Colloid and Interface Chemistry of Ministry of Education, The Modeling & Simulation Chemistry Division, School of Chemistry & Chemical Engineering, Shandong University, Jinan, 250100, P. R. China, and Department of Chemistry, Michigan State University, East Lansing, Michigan 48824
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67
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Wang CR, Luo T, Lu QB. On the lifetimes and physical nature of incompletely relaxed electrons in liquid water. Phys Chem Chem Phys 2008; 10:4463-70. [DOI: 10.1039/b806287k] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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68
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Borgis D, Rossky PJ, Turi L. Nuclear quantum effects on the nonadiabatic decay mechanism of an excited hydrated electron. J Chem Phys 2007; 127:174508. [DOI: 10.1063/1.2780868] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
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69
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Shkrob IA. On the nature of infrared absorbing trapped electron center in low-temperature ice-Ih. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.06.111] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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70
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Thaller A, Laenen R, Laubereau A. The precursors of the solvated electron in methanol studied by femtosecond pump-repump-probe spectroscopy. J Chem Phys 2007; 124:024515. [PMID: 16422619 DOI: 10.1063/1.2155481] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Using UV photoionization and delayed near-infrared reexcitation pulses, a novel time-, frequency-, and polarization-resolved pump-repump-probe spectroscopy is conducted in the probing range of 450-2400 nm with improved experimental accuracy. Both the generation process and relaxation dynamics following selective repumping of intermediate species of the solvated electron are investigated and analyzed self-consistently with the help of a kinetic model. New insight in the intermediates of the trapped electron is gained leading to a unique microscopic picture.
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Affiliation(s)
- A Thaller
- Physik Department E11, Technische Universität München, D-85748 Garching, Germany.
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71
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Pratihar S, Chandra A. Electron solvation in water-ammonia mixed clusters: Structure, energetics, and the nature of localization states of the excess electron. J Chem Phys 2007; 126:234510. [PMID: 17600428 DOI: 10.1063/1.2741257] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The structure and energetics of water-ammonia mixed clusters with an excess electron, [(H2O)n(NH3)m]- with m=1, n=2-6 and m=2, n=2, and also the corresponding neutral clusters are investigated in detail by means of ab initio quantum chemical calculations. The authors focus on the localization structure of the excess electron with respect to its surface versus interiorlike states, its binding to ammonia versus water molecules, the spatial and orientational arrangement of solvent molecules around the excess electron, the changes of the overall hydrogen-bonded structure of the clusters as compared to those of the neutral ones and associated dipole moment changes, vertical detachment energies of the anionic clusters, and also the vertical attachment energies of the neutral clusters. It is found that the hydrogen-bonded structure of the anionic clusters are very different from those of the neutral clusters unlike the case of water-ammonia dimer anion, and these changes in structural arrangements lead to drastically different dipole moments of the anionic and the neutral clusters. The spatial distribution of the singly occupied molecular orbital holding the excess electron shows only surface states for the smaller clusters. However, for n=5 and 6, both surface and interiorlike binding states are found to exist for the excess electron. For the surface states, the excess electron can be bound to the dangling hydrogens of either an ammonia or a water molecule with different degrees of stability and vertical detachment energies. The interiorlike states, wherever they exist, are found to have a higher vertical detachment energy than any of the surface states of the same cluster. Also, for interiorlike states, the ammonia molecule with its dangling hydrogens is always found to stay on top or on a far side of the charge density of the excess electron without participating in the hydrogen bond network of the cluster; the intermolecular hydrogen bonds are formed by the water molecules only which add to the overall stability of these anionic clusters.
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Affiliation(s)
- Subha Pratihar
- Department of Chemistry, Indian Institute of Technology, Kanpur 208016, India
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72
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Madarász A, Rossky PJ, Turi L. Excess electron relaxation dynamics at water/air interfaces. J Chem Phys 2007; 126:234707. [PMID: 17600435 DOI: 10.1063/1.2741514] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have performed mixed quantum-classical molecular dynamics simulations of the relaxation of a ground state excess electron at interfaces of different phases of water with air. The investigated systems included ambient water/air, supercooled water/air, Ih ice/air, and amorphous solid water/air interfaces. The present work explores the possible connections of the examined interfacial systems to finite size cluster anions and the three-dimensional infinite, fully hydrated electron. Localization site analyses indicate that in the absence of nuclear relaxation the electron localizes in a shallow potential trap on the interface in all examined systems in a diffuse, surface-bound (SB) state. With relaxation, the weakly bound electron undergoes an ultrafast localization and stabilization on the surface with the concomitant collapse of its radius. In the case of the ambient liquid interface the electron slowly (on the 10 ps time scale) diffuses into the bulk to form an interior-bound state. In each other case, the excess electron persists on the interface in SB states. The relaxation dynamics occur through distinct SB structures which are easily distinguishable by their energetics, geometries, and interactions with the surrounding water bath. The systems exhibiting the most stable SB excess electron states (supercooled water/air and Ih ice/air interfaces) are identified by their characteristic hydrogen-bonding motifs which are found to contain double acceptor-type water molecules in the close vicinity of the electron. These surface states correlate reasonably with those extrapolated to infinite size from simulated water cluster anions.
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Affiliation(s)
- Adám Madarász
- Department of Physical Chemistry, Eötvös Loránd University, Budapest 112, P.O. Box 32, Budapest H-1518, Hungary
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73
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74
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Ungar LW, Cina JA. Short-Time Fluorescence Stokes Shift Dynamics. ADVANCES IN CHEMICAL PHYSICS 2007. [DOI: 10.1002/9780470141595.ch2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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75
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Polar and Nonpolar Solvation Dynamics, Ion Diffusion, and Vibrational Relaxation: Role of Biphasic Solvent Response in Chemical Dynamics. ADVANCES IN CHEMICAL PHYSICS 2007. [DOI: 10.1002/9780470141687.ch4] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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76
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Domcke W, Stock G. Theory of Ultrafast Nonadiabatic Excited-State Processes and their Spectroscopic Detection in Real Time. ADVANCES IN CHEMICAL PHYSICS 2007. [DOI: 10.1002/9780470141595.ch1] [Citation(s) in RCA: 250] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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77
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Sobolewski AL, Domcke W. Computational studies of aqueous-phase photochemistry and the hydrated electron in finite-size clusters. Phys Chem Chem Phys 2007; 9:3818-29. [PMID: 17637974 DOI: 10.1039/b704066k] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A survey of recent ab initio calculations on excited electronic states of water clusters and various chromophore-water clusters is given. Electron and proton transfer processes in these systems have been characterized by the determination of electronic wave functions, minimum-energy reaction paths and potential-energy profiles. It is pointed out that the transfer of a neutral hydrogen atom (leading to biradicals) rather than the transfer of a proton (leading to ion pairs) is the generic excited-state reaction mechanism in these systems. The hydrated hydronium radical, (H3O)(aq), plays a central role in this scenario. The electronic and vibrational spectra of H3O(H2O)(n) clusters and the decay mechanism of these metastable species have been investigated in some detail. The results suggest that (H3O)(aq) could be the carrier of the characteristic spectroscopic properties of the hydrated electron in liquid water.
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78
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Bedard-Hearn MJ, Larsen RE, Schwartz BJ. Moving solvated electrons with light: Nonadiabatic mixed quantum/classical molecular dynamics simulations of the relocalization of photoexcited solvated electrons in tetrahydrofuran (THF). J Chem Phys 2006; 125:194509. [PMID: 17129125 DOI: 10.1063/1.2358131] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Motivated by recent ultrafast spectroscopic experiments [Martini et al., Science 293, 462 (2001)], which suggest that photoexcited solvated electrons in tetrahydrofuran (THF) can relocalize (that is, return to equilibrium in solvent cavities far from where they started), we performed a series of nonequilibrium, nonadiabatic, mixed quantum/classical molecular dynamics simulations that mimic one-photon excitation of the THF-solvated electron. We find that as photoexcited THF-solvated electrons relax to their ground states either by continuous mixing from the excited state or via nonadiabatic transitions, approximately 30% of them relocalize into cavities that can be over 1 nm away from where they originated, in close agreement with the experiments. A detailed investigation shows that the ability of excited THF-solvated electrons to undergo photoinduced relocalization stems from the existence of preexisting cavity traps that are an intrinsic part of the structure of liquid THF. This explains why solvated electrons can undergo photoinduced relocalization in solvents like THF but not in solvents like water, which lack the preexisting traps necessary to stabilize the excited electron in other places in the fluid. We also find that even when they do not ultimately relocalize, photoexcited solvated electrons in THF temporarily visit other sites in the fluid, explaining why the photoexcitation of THF-solvated electrons is so efficient at promoting recombination with nearby scavengers. Overall, our study shows that the defining characteristic of a liquid that permits the photoassisted relocalization of solvated electrons is the existence of nascent cavities that are attractive to an excess electron; we propose that other such liquids can be found from classical computer simulations or neutron diffraction experiments.
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Affiliation(s)
- Michael J Bedard-Hearn
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, USA
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79
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Tachikawa H. Electron hydration dynamics in water clusters: A direct ab initio molecular dynamics approach. J Chem Phys 2006; 125:144307. [PMID: 17042590 DOI: 10.1063/1.2348870] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Electron attachment dynamics of excess electron in water cluster (H2O)n (n = 2 and 3) have been investigated by means of full-dimensional direct ab initio molecular dynamics (MD) method at the MP26-311++G(d,p) level. It was found that the hydrogen bond breaking due to the excess electron is an important process in the first stage of electron capture in water trimer. Time scale of electron localization and hydrogen bond breaking were determined by the direct ab initio MD simulation. The initial process of hydration in water cluster is clearly visualized in the present study. In n = 3, an excess electron is first trapped around the cyclic water trimer with a triangular form, where the excess electron is equivalently distributed on the three water molecules at time zero. After 50 fs, the excess electron is concentrated into two water molecules, while the potential energy of the system decreases by -1.5 kcal/mol from the vertical point. After 100 fs, the excess electron is localized in one of the water molecules and the potential energy decreases by -5.3 kcal/mol, but the triangular form still remained. After that, one of the hydrogen bonds in the triangular form is gradually broken by the excess electron, while the structure becomes linear at 100-300 fs after electron capture. The time scale of hydrogen bond breaking due to the excess electron is calculated to be about 300 fs. Finally, a dipole bound state is formed by the linear form of three water molecules. In the case of n = 2, the dipole bound anion is formed directly. The mechanism of electron hydration dynamics was discussed on the basis of theoretical results.
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Affiliation(s)
- Hiroto Tachikawa
- Division of Molecular Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan.
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80
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Abstract
Experiments are reviewed in which key problems in chemical dynamics are probed by experiments based on photodetachment and/or photoexcitation of negative ions. Examples include transition state spectroscopy of biomolecular reactions, spectroscopy of open shell van der Waals complexes, photodissociation of free radicals, and time-resolved dynamics in clusters. The experimental methods used in these investigations are described along with representative systems that have been studied.
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Affiliation(s)
- Daniel M Neumark
- Department of Chemistry,University of California, Berkeley, California 94720, USA.
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81
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Bedard-Hearn MJ, Larsen RE, Schwartz BJ. Projections of quantum observables onto classical degrees of freedom in mixed quantum-classical simulations: understanding linear response failure for the photoexcited hydrated electron. PHYSICAL REVIEW LETTERS 2006; 97:130403. [PMID: 17026014 DOI: 10.1103/physrevlett.97.130403] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2006] [Indexed: 05/12/2023]
Abstract
We present a general analytic method for understanding how specific motions of a classical bath influence the dynamics of quantum-mechanical observables in mixed quantum-classical molecular dynamics simulations. We apply our method and develop expressions for the special case of quantum solvation, allowing us to examine how specific classical solvent motions couple to the equilibrium energy fluctuations and nonequilibrium energy relaxation of a quantum-mechanical solute. As a first application of our formalism, we investigate the motions of classical water underlying the equilibrium and nonequilibrium excited-state solvent response functions of the hydrated electron; the results allow us to explain why the linear response approximation fails for this system.
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Affiliation(s)
- Michael J Bedard-Hearn
- Department of Chemistry and Biochemistry, University of California-Los Angeles, 607 Charles E. Young Drive East, Los Angeles, CA 90095-1569, USA
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82
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Borgis D, Rossky PJ, Turi L. Quantized time correlation function approach to nonadiabatic decay rates in condensed phase: Application to solvated electrons in water and methanol. J Chem Phys 2006; 125:64501. [PMID: 16942292 DOI: 10.1063/1.2221685] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
A new, alternative form of the golden rule formula defining the nonadiabatic transition rate between two quantum states in condensed phase is presented. The formula involves the quantum time correlation function of the energy gap, of the nonadiabatic coupling, and their cross terms. Those quantities can be inferred from their classical counterparts, determined via molecular dynamics simulations. The formalism is applied to the problem of the nonadiabatic p-->s relaxation of an equilibrated p-electron in water and methanol. We find that, in both solvents, the relaxation is induced by the coupling to the vibrational modes and the quantum effects modify the rate by a factor of 2-10 depending on the quantization procedure applied. The resulting p-state lifetime for a hypothetical equilibrium excited state appears extremely short, in the sub-100 fs regime. Although this result is in contrast with all previous theoretical predictions, we also illustrate that the lifetimes computed here are very sensitive to the simulated electronic quantum gap and to the strongly correlated nonadiabatic coupling.
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Affiliation(s)
- Daniel Borgis
- Département Physique et Modélisation, Université d'Evry-Val-d'Essone, Boulevard François Mitterand, 91025 Evry, France.
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83
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Larsen RE, Schwartz BJ. Nonadiabatic Molecular Dynamics Simulations of Correlated Electrons in Solution. 1. Full Configuration Interaction (CI) Excited-State Relaxation Dynamics of Hydrated Dielectrons. J Phys Chem B 2006; 110:9681-91. [PMID: 16686519 DOI: 10.1021/jp055322+] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The hydrated dielectron is composed of two excess electrons dissolved in liquid water that occupy a single cavity; in both its singlet and triplet spin states there is a significant exchange interaction so the two electrons cannot be considered to be independent. In this paper and the following paper,we present the results of mixed quantum/classical molecular dynamics simulations of the nonadiabatic relaxation dynamics of photoexcited hydrated dielectrons, where we use full configuration interaction (CI) to solve for the two-electron wave function at every simulation time step. To the best of our knowledge, this represents the first systematic treatment of excited-state solvation dynamics where the multiple-electron problem is solved exactly. The simulations show that the effects of exchange and correlation contribute significantly to the relaxation dynamics. For example, spin-singlet dielectrons relax to the ground state on a time scale similar to that of single electrons excited at the same energy, but spin-triplet dielectrons relax much faster. The difference in relaxation dynamics is caused by exchange and correlation: The Pauli exclusion principle imposes very different electronic structure when the electrons' spins are singlet paired than when they are triplet paired, altering the available nonadiabatic relaxation pathways. In addition, we monitor how electronic correlation changes dynamically during nonadiabatic relaxation and show that solvent dynamics cause electron correlation to evolve quite differently for singlet and triplet dielectrons. Despite such differences, our calculations show that both spin states are stable to excited-state dissociation, but that the excited-state stability has different origins for the two spin states. For singlet dielectrons, the stability depends on whether the solvent structure can rearrange to create a second cavity before the ground state is reached. For triplet dielectrons, in contrast, electronic correlation ensures that the two electrons do not dissociate, even if the dielectron is artificially kept from reaching the ground state. In addition, both singlet and triplet dielectrons change shape dramatically during relaxation, so that linear response fails to describe the solvation dynamics for either spin state. In the following paper (Larsen, R. E.; Schwartz, B. J. J. Phys. Chem. B 2006, 110, 9692), we use these simulations to calculate the pump-probe spectroscopic signal expected for photoexcited hydrated dielectrons and to predict an experiment to observe hydrated dielectrons directly.
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Affiliation(s)
- Ross E Larsen
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, CA 90095-1569, USA
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84
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Larsen RE, Schwartz BJ. Nonadiabatic Molecular Dynamics Simulations of Correlated Electrons in Solution. 2. A Prediction for the Observation of Hydrated Dielectrons with Pump−Probe Spectroscopy. J Phys Chem B 2006; 110:9692-7. [PMID: 16686520 DOI: 10.1021/jp0553232] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The hydrated dielectron is a highly correlated, two-electron, solvent-supported state consisting of two spin-paired electrons confined to a single cavity in liquid water. Although dielectrons have been predicted to exist theoretically and have been used to explain the lack of ionic strength effect in the bimolecular reaction kinetics of hydrated electrons, they have not yet been observed directly. In this paper, we use the extensive nonadiabatic mixed quantum/classical excited-state molecular dynamics simulations from the previous paper to calculate the transient spectroscopy of hydrated dielectrons. Because our simulations use full configuration interaction (CI) to determine the ground and excited state two-electron wave functions at every instant, our nonequilibrium simulations allow us to compute the absorption, stimulated emission (SE), and bleach spectroscopic signals of both singlet and triplet dielectrons following excitation by ultraviolet light. Excited singlet dielectrons are predicted to display strong SE in the mid infrared and a transient absorption in the near-infrared. The near-infrared transient absorption of the singlet dielectron, which occurs near the peak of the (single) hydrated electron's equilibrium absorption, arises because the two electrons tend to separate in the excited state. In contrast, excitation of the hydrated electron gives a bleach signal in this wavelength region. Thus, our calculations suggest a clear pump-probe spectroscopic signature that may be used in the laboratory to distinguish hydrated singlet dielectrons from hydrated electrons: By choosing an excitation energy that is to the blue of the peak of the hydrated electron's absorption spectrum and probing near the maximum of the single electron's absorption, the single electron's transient bleach signal should shrink or even turn into a net absorption as sample conditions are varied to produce more dielectrons.
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Affiliation(s)
- Ross E Larsen
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, CA 90095-1569, USA
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85
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Zharikov AA, Fischer SF. Theory of electron solvation in polar liquids: A continuum model. J Chem Phys 2006; 124:054506. [PMID: 16468893 DOI: 10.1063/1.2165198] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The solvation of electrons in polar liquids is analyzed on the basis of an extended continuum model. In addition to the long-range electron-dipole interaction two short-range interactions are introduced. Among others one accounts for interactions with groups capable of forming hydrogen bonds and the second for quadrupolar characteristics of the liquid molecules. Both are induced by the orientation of the molecular dipole. Applying the scaling method a proper reaction coordinate is introduced and the solvation dynamics are discussed for the electron in the electronic ground state and after excitation to the p-type excited state. The observed spectral evolution of the transient absorption spectra, after two photon excitations for electrons in water and in methanol, is well described by this theory. An analytic estimate for the nonradiative deactivation from the electronically excited solvated electron is found to be consistent with an observed lifetime of 50 fs for the electron in water. The theory predicts an about three times slower internal conversion in methanol as solvent in comparison with water.
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Affiliation(s)
- Anatoly A Zharikov
- Physik Department T-38, Technische Universität München, D-85748 Garching, Germany.
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86
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Bragg AE, Verlet JRR, Kammrath A, Cheshnovsky O, Neumark DM. Electronic Relaxation Dynamics of Water Cluster Anions. J Am Chem Soc 2005; 127:15283-95. [PMID: 16248671 DOI: 10.1021/ja052811e] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The electronic relaxation dynamics of water cluster anions, (H(2)O)(n)(-), have been studied with time-resolved photoelectron imaging. In this investigation, the excess electron was excited through the p<--s transition with an ultrafast laser pulse, with subsequent electronic evolution monitored by photodetachment. All excited-state lifetimes exhibit a significant isotope effect (tau(D)2(O)/tau(H)2(O) approximately 2). Additionally, marked dynamical differences are found for two classes of water cluster anions, isomers I and II, previously assigned as clusters with internally solvated and surface-bound electrons, respectively. Isomer I clusters with n > or = 25 decay exclusively by internal conversion, with relaxation times that extrapolate linearly with 1/n toward an internal conversion lifetime of 50 fs in bulk water. Smaller isomer I clusters (13 < or = n < or = 25) decay through a combination of excited-state autodetachment and internal conversion. The relaxation of isomer II clusters shows no significant size dependence over the range of n = 60-100, with autodetachment an important decay channel following excitation of these clusters. Photoelectron angular distributions (PADs) were measured for isomer I and isomer II clusters. The large differences in dynamical trends, relaxation mechanisms, and PADs between large isomer I and isomer II clusters are consistent with their assignment to very different electron binding motifs.
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Affiliation(s)
- Arthur E Bragg
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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87
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Affiliation(s)
- Biman Bagchi
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
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88
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Turi L, Sheu WS, Rossky PJ. Characterization of excess electrons in water-cluster anions by quantum simulations. Science 2005; 309:914-7. [PMID: 16081731 DOI: 10.1126/science.1115808] [Citation(s) in RCA: 182] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Water-cluster anions can serve as a bridge to understand the transition from gaseous species to the bulk hydrated electron. However, debate continues regarding how the excess electron is bound in (H2O)-n, as an interior, bulklike, or surface electronic state. To address the uncertainty, the properties of (H2O)-n clusters with 20 to 200 water molecules have been evaluated by mixed quantum-classical simulations. The theory reproduces every observed energetic, spectral, and structural trend with cluster size that is seen in experimental photoelectron and optical absorption spectra. More important, surface states and interior states each manifest a characteristic signature in the simulation data. The results strongly support assignment of surface-bound electronic states to the water-cluster anions in published experimental studies thus far.
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Affiliation(s)
- László Turi
- Eötvös Loránd University, Department of Physical Chemistry, Budapest 112, Post Office Box 32, H-1518, Hungary
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89
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Bernardi E, Marques Martins M, Stassen H. The breakdown of linear response theory in non-polar solvation dynamics. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2005.03.067] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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90
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Bedard-Hearn MJ, Larsen RE, Schwartz BJ. The role of solvent structure in the absorption spectrum of solvated electrons: Mixed quantum/classical simulations in tetrahydrofuran. J Chem Phys 2005; 122:134506. [PMID: 15847480 DOI: 10.1063/1.1867378] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In polar fluids such as water and methanol, the peak of the solvated electron's absorption spectrum in the red has been assigned as a sum of transitions between an s-like ground state and three nearly degenerate p-like excited states bound in a quasispherical cavity. In contrast, in weakly polar solvents such as tetrahydrofuran (THF), the solvated electron has an absorption spectrum that peaks in the mid-infrared, but no definitive assignment has been offered about the origins of the spectrum or the underlying structure. In this paper, we present the results of adiabatic mixed quantum/classical molecular dynamic simulations of the solvated electron in THF, and provide a detailed explanation of the THF-solvated electron's absorption spectrum and electronic structure. Using a classical solvent model and a fully quantum mechanical excess electron, our simulations show that although the ground and first excited states are bound in a quasispherical cavity, a multitude of other, nearby solvent cavities support numerous, nearly degenerate, bound excited states that have little Franck-Condon overlap with the ground state. We show that these solvent cavities, which are partially polarized so that they act as electron trapping sites, are an inherent property of the way THF molecules pack in the liquid. The absorption spectrum is thus assigned to a sum of bound-to-bound transitions between a localized ground state and multiple disjoint excited states scattered throughout the fluid. Furthermore, we find that the usual spherical harmonic labels (e.g., s-like, p-like) are not good descriptors of the excited-state wave functions of the solvated electron in THF. Our observation of multiple disjoint excited states is consistent with femtosecond pump-probe experiments in the literature that suggest that photoexcitation of solvated electrons in THF causes them to relocalize into solvent cavities far from where they originated.
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Affiliation(s)
- Michael J Bedard-Hearn
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095-1569, USA
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91
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Direct observation of elementary radical events: low- and high-energy radiation femtochemistry in solutions. Radiat Phys Chem Oxf Engl 1993 2005. [DOI: 10.1016/j.radphyschem.2004.06.014] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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92
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Cavity size effects on charge-transfer-to-solvent precursor excited states of internal halide water clusters X−(H2O)6. Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2004.09.138] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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93
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Bragg AE, Verlet JRR, Kammrath A, Cheshnovsky O, Neumark DM. Hydrated Electron Dynamics: From Clusters to Bulk. Science 2004; 306:669-71. [PMID: 15375222 DOI: 10.1126/science.1103527] [Citation(s) in RCA: 203] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The electronic relaxation dynamics of size-selected (H2O)n-/(D2O)n[25 </= n </= 50] clusters have been studied with time-resolved photoelectron imaging. The excess electron (ec-) was excited through the ec-(p)<--ec-(s) transition with an ultrafast laser pulse, with subsequent evolution of the excited state monitored with photodetachment and photoelectron imaging. All clusters exhibited p-state population decay with concomitant s-state repopulation (internal conversion) on time scales ranging from 180 to 130 femtoseconds for (H2O)n- and 400 to 225 femtoseconds for (D2O)n-; the lifetimes decrease with increasing cluster sizes. Our results support the "nonadiabatic relaxation" mechanism for the bulk hydrated electron (eaq-), which invokes a 50-femtosecond eaq-(p)-->eaq-(s(dagger)) internal conversion lifetime.
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Affiliation(s)
- A E Bragg
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
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94
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Cavanagh MC, Martini IB, Schwartz BJ. Revisiting the pump–probe polarized transient hole-burning of the hydrated electron: Is its absorption spectrum inhomogeneously broadened? Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2004.07.109] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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95
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Larsen RE, Schwartz BJ. Mixed Quantum/Classical Molecular Dynamics Simulations of the Hydrated Dielectron: The Role of Exchange in Condensed-Phase Structure, Dynamics, and Spectroscopy. J Phys Chem B 2004. [DOI: 10.1021/jp048951c] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ross E. Larsen
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569
| | - Benjamin J. Schwartz
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569
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96
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97
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Turi L, Rossky PJ. Critical evaluation of approximate quantum decoherence rates for an electronic transition in methanol solution. J Chem Phys 2004; 120:3688-98. [PMID: 15268531 DOI: 10.1063/1.1642609] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a quantum molecular dynamics calculation of a semiclassical decoherence function to evaluate the accuracy of alternative short-time approximations for coherence loss in the dynamics of condensed phase electronically nonadiabatic processes. The semiclassical function from mixed quantum-classical molecular dynamics simulations and frozen Gaussian wave packets is computed for the electronic transition of an excited state excess electron to the ground state in liquid methanol. The decoherence function decays on a 10 fs time scale that is qualitatively similar to the aqueous case. We demonstrate that it is the motion of the hydrogen atom, and, in particular, the hydrogen rotation around the oxygen-methyl bond which is predominantly responsible for destroying the quantum correlations between alternative states. Multiple time scales due to the slower diffusive nuclear modes, which dominate the solvation response of methanol, do not contribute to the coherence loss. The choice of the coordinate representation is investigated in detail and concluded to be irrelevant to the decay. Changes in both nuclear momenta and positions on the two alternative potential surfaces are found to contribute to decoherence, the former dominating at short times (t < 5 fs), the latter controlling the decay at longer times. Various short-time approximations to the full dynamics for the decoherence function are tested for the first time. The present treatment rigorously develops the short-time description and establishes its range of validity. Whereas the lowest-order short-time approximation proves to be a very good approximation up to about 5 fs, we also find that it bounds the decay of the decoherence function. After 5 fs, the coherence decay in fact becomes faster than the single Gaussian predicted in the lowest-order short-time limit. This decay is well reflected by an enhanced low-order approximation, which is also easily computed from equilibrium classical forces.
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Affiliation(s)
- László Turi
- Eötvös Loránd University, Department of Physical Chemistry, Budapest 112, PO Box 32, H-1518, Hungary.
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98
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Brooksby C, Prezhdo OV, Reid PJ. Molecular dynamics study of the weakly solvent dependent relaxation dynamics following chlorine dioxide photoexcitation. J Chem Phys 2003. [DOI: 10.1063/1.1614203] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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99
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Larsen RE, Schwartz BJ. Efficient real-space configuration-interaction method for the simulation of multielectron mixed quantum and classical nonadiabatic molecular dynamics in the condensed phase. J Chem Phys 2003. [DOI: 10.1063/1.1610438] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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100
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Rodriguez J, Skaf MS, Laria D. Solvation of excess electrons in supercritical ammonia. J Chem Phys 2003. [DOI: 10.1063/1.1601215] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
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