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Chaudhuri RK, Chattopadhyay S. A Fock space coupled cluster based probing of the single- and double-ionization profiles for the poly-cyclic aromatic hydrocarbons and conjugated polyenes. J Chem Phys 2021; 154:114106. [PMID: 33752359 DOI: 10.1063/5.0037557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Sequential formation of a poly-cyclic aromatic hydrocarbon (PAH) dication in the H I regions of the interstellar medium (ISM) is proposed to be a function of internal energy of the doubly ionized PAHs, which, in turn, is dependent on the single- and double-ionization potentials of the system. This sets a limit on the single- and double-ionization energies of the system(s) that can further undergo sequential absorption of two photons, leading to a dication (PAH+2). Here, we report the single-ionization (I+1) and double-ionization (I+2) energies and the I+2/I+1 ratio for some selected PAHs and conjugated polyenes obtained using the Fock space coupled cluster technique, enabling simultaneous consideration of several electronic states of different characters. The I+2 to I+1 ratio bears a constant ratio, giving allowance to determine I+2 from the knowledge of single-ionization (I+1) and vice versa. Our observations are in good agreement with the established literature findings, confirming the reliability of our estimates. The measured single- and double-ionization energies further demonstrate that the sequential formation and fragmentation of a PAH dication in the H I regions of the ISM for systems such as benzene and conjugated polyenes such as ethylene and butadiene are quite unlikely because I+2-I+1 for such system(s) is higher than the available photon energy in the H I regions of the ISM. Present findings may be useful to understand the formation and underlying decay mechanisms of multiply charged ions from PAHs and related compounds that may accentuate the exploration of the phenomenon of high-temperature superconductivity.
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Affiliation(s)
| | - Sudip Chattopadhyay
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103, India
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Sinha Ray S, Ghosh P, Chaudhuri RK, Chattopadhyay S. Improved virtual orbitals in state specific multireference perturbation theory for prototypes of quasidegenerate electronic structure. J Chem Phys 2017; 146:064111. [DOI: 10.1063/1.4975322] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Ghosh A, Chaudhuri RK, Chattopadhyay S, Mahapatra US. Relativistic state-specific multireference perturbation theory incorporating improved virtual orbitals: Application to the ground state single-bond dissociation. J Comput Chem 2015; 36:1954-72. [PMID: 26272333 DOI: 10.1002/jcc.24037] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 07/01/2015] [Accepted: 07/02/2015] [Indexed: 11/07/2022]
Abstract
Using four-component (4c) relativistic spinors, we present a computationally economical relativistic ab initio method for molecular systems employing our recently proposed second-order state-specific multireference perturbation theory (SSMRPT) incorporating the improved virtual orbital-complete active space configuration interaction (IVO-CASCI) reference wavefunction. The resulting method, 4c-IVO-SSMRPT [calculate one state at a time] is tested in pilot calculations on the homonuclear dimers including Li(2), Na(2), K(2), Rb(2), F(2), Cl(2), and Br(2) through the computations of the ground state potential energy curves (PECs). As SSMRPT curbs intruder effects, 4c-IVO-SSMRPT is numerically stable. To our knowledge, the SSMRPT in the 4c relativistic framework has not been explored in the past. Selective spectroscopic constants that are closely related to the correct shape and accuracy of the energy surfaces have been extracted from the computed PECs. For the halogen molecules, a relativistic destabilization of the bond has been found. Relativistic and electron correlation effects need to be incorporated to get reliable estimates. Our results are in good accordance with reference theoretical and experimental data which manifests the computational accuracy and efficiency of the new 4c-IVO-SSMRPT method. The method opens for an improved description of MR systems containing heavy elements. The inexpensiveness of IVO-CASCI makes 4c-IVO-SSMRPT method promising for studies on large systems of heavy elements.
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Affiliation(s)
- Anirban Ghosh
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, 711103, India
| | - Rajat K Chaudhuri
- Theory Group, Indian Institute of Astrophysics, Bangalore, 560034, India
| | - Sudip Chattopadhyay
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, 711103, India
| | - Uttam Sinha Mahapatra
- Department of Physics, Maulana Azad College, 8 Rafi Ahmed Kidwai Road, Kolkata, 700013, India
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Chattopadhyay S, Chaudhuri RK, Mahapatra US. State-specific multireference perturbation theory with improved virtual orbitals: Taming the ground state of F2, Be2,and N2. J Comput Chem 2015; 36:907-25. [DOI: 10.1002/jcc.23873] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 01/09/2015] [Accepted: 01/11/2015] [Indexed: 11/07/2022]
Affiliation(s)
- Sudip Chattopadhyay
- Department of Chemistry; Indian Institute of Engineering Science and Technology; Shibpur Howrah 711103 India
| | | | - Uttam Sinha Mahapatra
- Department of Physics; Maulana Azad College; 8 Rafi Ahmed Kidwai Road Kolkata 700013 India
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Ma Y, Ma H. Assessment of various natural orbitals as the basis of large active space density-matrix renormalization group calculations. J Chem Phys 2013; 138:224105. [DOI: 10.1063/1.4809682] [Citation(s) in RCA: 31] [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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Lu Z, Matsika S. High-Multiplicity Natural Orbitals in Multireference Configuration Interaction for Excited State Potential Energy Surfaces. J Phys Chem A 2013; 117:7421-30. [DOI: 10.1021/jp401444c] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Zhen Lu
- Department of Chemistry,
Temple University, Philadelphia,
Pennsylvania 19122, United States
| | - Spiridoula Matsika
- Department of Chemistry,
Temple University, Philadelphia,
Pennsylvania 19122, United States
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Chaudhuri RK, Freed KF, Chattopadhyay S, Mahapatra US. Theoretical Studies of the Ground and Excited State Structures of Stilbene. J Phys Chem A 2013; 117:9424-34. [DOI: 10.1021/jp311493w] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
| | - Karl F. Freed
- The James Franck
Institute and Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United
States
| | - Sudip Chattopadhyay
- Department of Chemistry,
Bengal Engineering and Science
University, Shibpur, Howrah 711103, India
| | - Uttam Sinha Mahapatra
- Department of Physics, Maulana Azad College, 8 Rafi Ahmed Kidwai Road, Kolkata
700013, India
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Fukuda R, Ehara M. Electronic excited states and electronic spectra of biphenyl: a study using many-body wavefunction methods and density functional theories. Phys Chem Chem Phys 2013; 15:17426-34. [DOI: 10.1039/c3cp52636d] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Lu Z, Matsika S. High-Multiplicity Natural Orbitals in Multireference Configuration Interaction for Excited States. J Chem Theory Comput 2012; 8:509-17. [DOI: 10.1021/ct200832u] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Zhen Lu
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Spiridoula Matsika
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
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Chaudhuri RK, Freed KF, Chattopadhyay S, Mahapatra US. Application of an efficient multireference approach to free-base porphin and metalloporphyrins: Ground, excited, and positive ion states. J Chem Phys 2011; 135:084118. [DOI: 10.1063/1.3627153] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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Chattopadhyay S, Chaudhuri RK, Freed KF. Prediction of electronic structure of organic radicaloid anions using efficient, economical multireference gradient approach. Phys Chem Chem Phys 2011; 13:7514-23. [PMID: 21423953 DOI: 10.1039/c0cp02106g] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The improved virtual orbital-complete active space configuration interaction (IVO-CASCI) method enables an economical and reasonably accurate treatment of static correlation in systems with significant multireference character, even when using a moderate basis set. This IVO-CASCI method supplants the computationally more demanding complete active space self-consistent field (CASSCF) method by producing comparable accuracy with diminished computational effort because the IVO-CASCI approach does not require additional iterations beyond an initial SCF calculation, nor does it encounter convergence difficulties or multiple solutions that may be found in CASSCF calculations. Our IVO-CASCI analytical gradient approach is applied to compute the equilibrium geometry for the ground and lowest excited state(s) of the theoretically very challenging 2,6-pyridyne, 1,2,3-tridehydrobenzene and 1,3,5-tridehydrobenzene anionic systems for which experiments are lacking, accurate quantum calculations are almost completely absent, and commonly used calculations based on single reference configurations fail to provide reasonable results. Hence, the computational complexity provides an excellent test for the efficacy of multireference methods. The present work clearly illustrates that the IVO-CASCI analytical gradient method provides a good description of the complicated electronic quasi-degeneracies during the geometry optimization process for the radicaloid anions. The IVO-CASCI treatment produces almost identical geometries as the CASSCF calculations (performed for this study) at a fraction of the computational labor. Adiabatic energy gaps to low lying excited states likewise emerge from the IVO-CASCI and CASSCF methods as very similar. We also provide harmonic vibrational frequencies to demonstrate the stability of the computed geometries.
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Affiliation(s)
- Sudip Chattopadhyay
- Department of Chemistry, Bengal Engineering and Science University, Shibpur, Howrah 711103, India.
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Chattopadhyay S, Chaudhuri RK, Freed KF. Geometry Optimization of Radicaloid Systems Using Improved Virtual Orbital-Complete Active Space Configuration Interaction (IVO-CASCI) Analytical Gradient Method. J Phys Chem A 2010; 115:3665-78. [DOI: 10.1021/jp103536w] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Sudip Chattopadhyay
- Department of Chemistry, Bengal Engineering and Science University, Shibpur, Howrah 711103, India
| | | | - Karl F. Freed
- The James Franck Institute and Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
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