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Manzhos S, Carrington T, Laverdure L, Mosey N. Computing the Anharmonic Vibrational Spectrum of UF6 in 15 Dimensions with an Optimized Basis Set and Rectangular Collocation. J Phys Chem A 2015; 119:9557-67. [DOI: 10.1021/acs.jpca.5b07627] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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52
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Avila G, Carrington T. Using multi-dimensional Smolyak interpolation to make a sum-of-products potential. J Chem Phys 2015; 143:044106. [DOI: 10.1063/1.4926651] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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53
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Brown J, Carrington T. Using an iterative eigensolver to compute vibrational energies with phase-spaced localized basis functions. J Chem Phys 2015; 143:044104. [DOI: 10.1063/1.4926805] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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54
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Wang XG, Carrington T. The vibration-rotation-tunneling levels of N2-H2O and N2-D2O. J Chem Phys 2015; 143:024303. [PMID: 26178101 DOI: 10.1063/1.4923339] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In this paper, we report vibration-rotation-tunneling levels of the van der Waals clusters N2-H2O and N2-D2O computed from an ab initio potential energy surface. The only dynamical approximation is that the monomers are rigid. We use a symmetry adapted Lanczos algorithm and an uncoupled product basis set. The pattern of the cluster's levels is complicated by splittings caused by H-H exchange tunneling (larger splitting) and N-N exchange tunneling (smaller splitting). An interesting result that emerges from our calculation is that whereas in N2-H2O, the symmetric H-H tunnelling state is below the anti-symmetric H-H tunnelling state for both K = 0 and K = 1, the order is reversed in N2-D2O for K = 1. The only experimental splitting measurements are the D-D exchange tunneling splittings reported by Zhu et al. [J. Chem. Phys. 139, 214309 (2013)] for N2-D2O in the v2 = 1 region of D2O. Due to the inverted order of the split levels, they measure the sum of the K = 0 and K = 1 tunneling splittings, which is in excellent agreement with our calculated result. Other splittings we predict, in particular those of N2-H2O, may guide future experiments.
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Abstract
I review two new ideas for coping with the size of large product basis sets and large product grids when one computes vibrational energy levels. The first is based on a tensor reduction scheme. It exploits advantages of a sum-of-products potential. The key idea is to use a basis each of whose function is a sum of optimized products and to compress the number of terms in each basis function. When the potential does not have the sum-of-products form, it is usually necessary to use quadrature. The second idea uses a nondirect product grid that has structure and is therefore compatible with efficient matrix–vector products.
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Brown J, Carrington T. Comment on "Phase-space approach to solving the time-independent Schrödinger equation". PHYSICAL REVIEW LETTERS 2015; 114:058901. [PMID: 25699468 DOI: 10.1103/physrevlett.114.058901] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Indexed: 06/04/2023]
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57
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Wang XG, Carrington T. Using experimental data and a contracted basis Lanczos method to determine an accurate methane potential energy surface from a least squares optimization. J Chem Phys 2014; 141:154106. [DOI: 10.1063/1.4896569] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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58
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Roy TK, Carrington T, Gerber RB. Approximate first-principles anharmonic calculations of polyatomic spectra using MP2 and B3LYP potentials: comparisons with experiment. J Phys Chem A 2014; 118:6730-9. [PMID: 24977304 DOI: 10.1021/jp5060155] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Anharmonic vibrational spectroscopy calculations using MP2 and B3LYP computed potential surfaces are carried out for a series of molecules, and frequencies and intensities are compared with those from experiment. The vibrational self-consistent field with second-order perturbation correction (VSCF-PT2) is used in computing the spectra. The test calculations have been performed for the molecules HNO3, C2H4, C2H4O, H2SO4, CH3COOH, glycine, and alanine. Both MP2 and B3LYP give results in good accord with experimental frequencies, though, on the whole, MP2 gives very slightly better agreement. A statistical analysis of deviations in frequencies from experiment is carried out that gives interesting insights. The most probable percentage deviation from experimental frequencies is about -2% (to the red of the experiment) for B3LYP and +2% (to the blue of the experiment) for MP2. There is a higher probability for relatively large percentage deviations when B3LYP is used. The calculated intensities are also found to be in good accord with experiment, but the percentage deviations are much larger than those for frequencies. The results show that both MP2 and B3LYP potentials, used in VSCF-PT2 calculations, account well for anharmonic effects in the spectroscopy of molecules of the types considered.
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Wang XG, Carrington T. Rovibrational levels and wavefunctions of Cl−H2O. J Chem Phys 2014; 140:204306. [DOI: 10.1063/1.4875798] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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60
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Leclerc A, Carrington T. Calculating vibrational spectra with sum of product basis functions without storing full-dimensional vectors or matrices. J Chem Phys 2014; 140:174111. [DOI: 10.1063/1.4871981] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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61
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Brown J, Wang XG, Carrington T, Grubbs GS, Dawes R. Computational study of the rovibrational spectrum of CO2–CS2. J Chem Phys 2014; 140:114303. [DOI: 10.1063/1.4867792] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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62
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Ramakrishnan R, Carrington T. Vibrational energy levels of difluorodioxirane computed with variational and perturbative methods from a hybrid force field. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 119:107-112. [PMID: 23290829 DOI: 10.1016/j.saa.2012.11.104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 11/06/2012] [Accepted: 11/23/2012] [Indexed: 06/01/2023]
Abstract
We have computed vibrational energy levels of difluorodioxirane (CF2O2). For the potential, a Taylor expansion in normal coordinates is used. The CCSD(T) and MP2 methods and correlation consistent basis sets of quadruple-zeta quality are used to determine the force constants. The vibrational Schrödinger equation was solved using both a variational method and second order perturbation theory. The Watson kinetic energy operator and a discrete variable representation were used with the DEWE (E. Mátyus, G. Czakó, B.T. Sutcliffe and A.G. Császár, J. Chem. Phys. 127 (2007) 084102) computer program to do the variational calculations. For the variational calculations, the average absolute deviation of fundamentals, with respect to experimental values, is less than 3 cm(-1). Perturbative results are almost as good. About 300 vibrational levels were computed. (16)O→(18)O isotopic shifts have also been calculated variationally for the lowest 75 vibrational energy levels and are compared to experimental results.
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Brown J, Wang XG, Carrington T. Calculating and assigning rovibrational energy levels of (15N2O)2, (15N14NO)2, 14N2O-15N2O and 15N14NO-15N2O. Phys Chem Chem Phys 2013; 15:19159-68. [PMID: 24104969 DOI: 10.1039/c3cp52548a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this paper we report transition frequencies and rotational constants computed for several isotopologues of the nitrous oxide dimer. A previously reported intermolecular potential, the symmetry adapted Lanczos algorithm and an uncoupled product basis set are used to do the calculations. Rotational transition frequencies and rotational constants are in good agreement with experiment. We calculate states localized in both polar and nonpolar wells on the potential surface. Two of the four isotopologues we study have inequivalent monomers. They have wavefunctions localized over a single polar well.
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Avila G, Carrington T. Solving the Schroedinger equation using Smolyak interpolants. J Chem Phys 2013; 139:134114. [DOI: 10.1063/1.4821348] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [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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Bačić Z, Carrington T. Tribute to Joel M. Bowman. J Phys Chem A 2013; 117:6905-6. [DOI: 10.1021/jp405528s] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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66
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Manzhos S, Chan M, Carrington T. Communication: Favorable dimensionality scaling of rectangular collocation with adaptable basis functions up to 7 dimensions. J Chem Phys 2013; 139:051101. [DOI: 10.1063/1.4817182] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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67
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Wang XG, Carrington T. Computing rovibrational levels of polyatomic molecules with polyspherical coordinates and a contracted basis built with a K-independent vibrational primitive basis. Mol Phys 2013. [DOI: 10.1080/00268976.2013.808387] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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68
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Dawes R, Wang XG, Carrington T. CO Dimer: New Potential Energy Surface and Rovibrational Calculations. J Phys Chem A 2013; 117:7612-30. [DOI: 10.1021/jp404888d] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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69
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Jaquet R, Carrington T. Using a Nondirect Product Basis to Compute J > 0 Rovibrational States of H3+. J Phys Chem A 2013; 117:9493-500. [DOI: 10.1021/jp312027s] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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70
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Wang XG, Carrington T. Computing rovibrational levels of methane with curvilinear internal vibrational coordinates and an Eckart frame. J Chem Phys 2013; 138:104106. [DOI: 10.1063/1.4793474] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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71
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Chan M, Carrington T, Manzhos S. Anharmonic vibrations of the carboxyl group in acetic acid on TiO2: implications for adsorption mode assignment in dye-sensitized solar cells. Phys Chem Chem Phys 2013; 15:10028-34. [DOI: 10.1039/c3cp00065f] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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72
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Chan M, Yamashita K, Carrington T, Manzhos S. Towards Accurate Spectroscopic Identification of Species at Catalytic Surfaces: Anharmonic Vibrations of Formate on AuPt. ACTA ACUST UNITED AC 2012. [DOI: 10.1557/opl.2012.1623] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
ABSTRACTWe present a calculation of vibrational frequencies of formate on the AuPt(111) surface alloy including full anharmonicity and coupling of all six intramolecular degrees of freedom. This species is a key intermediate in methanol oxidation on this material. We use a modified version of the method of Manzhos and Carrington to compute the spectrum directly from a small number (<10,000) of DFT single-point energies, bypassing the construction of a potential energy surface. This is the first such calculation for a 4-atomic species at a surface. The spectrum is obtained using rectangular collocation and a small basis set of parameterized Hermite functions. The achievable accuracy of the order of several cm-1 corresponds to the typical experimental resolution. Using normal coordinates makes the equations simple and general and easily applicable to other systems. This calculation is doable on a PC. We predict that anharmonicity and coupling lower the fundamental frequencies by dozens of cm-1, which could affect species assignment.
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Avila G, Carrington T. Solving the vibrational Schrödinger equation using bases pruned to include strongly coupled functions and compatible quadratures. J Chem Phys 2012; 137:174108. [DOI: 10.1063/1.4764099] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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74
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Chan M, Manzhos S, Carrington T, Yamashita K. Parameterized Bases for Calculating Vibrational Spectra Directly from ab Initio Data Using Rectangular Collocation. J Chem Theory Comput 2012; 8:2053-61. [DOI: 10.1021/ct300248n] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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75
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Brown J, Wang XG, Dawes R, Carrington T. Computational study of the rovibrational spectrum of (OCS)2. J Chem Phys 2012; 136:134306. [DOI: 10.1063/1.3697679] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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