1
|
Levine BG, Durden AS, Esch MP, Liang F, Shu Y. CAS without SCF-Why to use CASCI and where to get the orbitals. J Chem Phys 2021; 154:090902. [PMID: 33685182 DOI: 10.1063/5.0042147] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The complete active space self-consistent field (CASSCF) method has seen broad adoption due to its ability to describe the electronic structure of both the ground and excited states of molecules over a broader swath of the potential energy surface than is possible with the simpler Hartree-Fock approximation. However, it also has a reputation for being unwieldy, computationally costly, and un-black-box. Here, we discuss a class of alternatives, complete active space configuration interaction (CASCI) methods, paying particular attention to their application to electronic excited states. The goal of this Perspective is fourfold. First, we argue that CASCI is not merely an approximation to CASSCF, in that it can be designed to have important qualitative advantages over CASSCF. Second, we present several insights drawn from our experience experimenting with different schemes for computing orbitals to be employed in CASCI. Third, we argue that CASCI is well suited for application to nanomaterials. Finally, we reason that, with the rise in new low-scaling approaches for describing multireference systems, there is a greater need than ever to develop new methods for defining orbitals that provide an efficient and accurate description of both static correlation and electronic excitations in a limited active space.
Collapse
Affiliation(s)
- Benjamin G Levine
- Institute for Advanced Computational Science and Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA
| | - Andrew S Durden
- Institute for Advanced Computational Science and Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA
| | - Michael P Esch
- Institute for Advanced Computational Science and Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA
| | - Fangchun Liang
- Institute for Advanced Computational Science and Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA
| | - Yinan Shu
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| |
Collapse
|
2
|
Manna S, Chaudhuri RK, Chattopadhyay S. Taming the excited states of butadiene, hexatriene, and octatetraene using state specific multireference perturbation theory with density functional theory orbitals. J Chem Phys 2020; 152:244105. [DOI: 10.1063/5.0007198] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Shovan Manna
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103, India
| | | | - Sudip Chattopadhyay
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103, India
| |
Collapse
|
3
|
Chattopadhyay S. Investigation of Multiple-Bond Dissociation Using Brillouin–Wigner Perturbation with Improved Virtual Orbitals. J Phys Chem A 2020; 124:1444-1463. [DOI: 10.1021/acs.jpca.9b11522] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sudip Chattopadhyay
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103, India
| |
Collapse
|
4
|
Sinha Ray S. Ab initio diagnosis of isomerization pathway of diphosphene and diphosphinylidene. Chem Phys 2020. [DOI: 10.1016/j.chemphys.2019.110555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
5
|
Manna S, Ray SS, Chattopadhyay S, Chaudhuri RK. A simplified account of the correlation effects to bond breaking processes: The Brillouin-Wigner perturbation theory using a multireference formulation. J Chem Phys 2019. [DOI: 10.1063/1.5097657] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Shovan Manna
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103, India
| | - Suvonil Sinha Ray
- Department of Chemistry, University of Calcutta, Kolkata 700009, India
| | - Sudip Chattopadhyay
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103, India
| | | |
Collapse
|
6
|
Wang S, Li C, Evangelista FA. Analytic gradients for the single-reference driven similarity renormalization group second-order perturbation theory. J Chem Phys 2019; 151:044118. [PMID: 31370522 DOI: 10.1063/1.5100175] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We derive and implement analytic energy gradients for the single-reference driven similarity renormalization group second-order perturbation theory (DSRG-PT2). The resulting equations possess an asymptotic scaling that is identical to that of the second-order Møller-Plesset perturbation theory (MP2), indicating that the exponential regularizer in the DSRG equations does not introduce formal difficulties in the gradient theory. We apply the DSRG-PT2 method to optimizing the geometries of 15 small molecules. The equilibrium bond lengths computed with DSRG-PT2 are found similar to those of MP2, yielding a mean absolute error of 0.0033 Å and a standard deviation of 0.0045 Å when compared with coupled cluster with singles, doubles, and perturbative triples.
Collapse
Affiliation(s)
- Shuhe Wang
- Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA
| | - Chenyang Li
- Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA
| | - Francesco A Evangelista
- Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA
| |
Collapse
|
7
|
Chattopadhyay S. Simplified Treatment of Electronic Structures of the Lowest Singlet and Triplet States of Didehydropyrazines. J Phys Chem A 2019; 123:5980-5994. [DOI: 10.1021/acs.jpca.9b03998] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Sudip Chattopadhyay
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103, India
| |
Collapse
|
8
|
Chattopadhyay S. Ab Initio Probing of the Ground State of Tetraradicals: Breakdown of Hund's Multiplicity Rule. J Phys Chem A 2019; 123:2211-2226. [PMID: 30794415 DOI: 10.1021/acs.jpca.8b10514] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The electronic structure of organic σ-type polyradical including 2,4,6-tridehydropyridine radical cation (246-TDHP) and three isomers of tetradehydrobenzene (TDHB) have been studied using a computationally robust and cost-effective second-order multireference perturbative model which provides a balanced treatment of nondynamic and dynamic contributions to the electron correlation problem in the ground or excited electronic states which are imperative for predicting structural properties (e.g., ground state multiplicity, energy gaps between high-spin and low-spin states, etc.) of polyradicals. Energy gaps are useful to capture insight into the degree of interaction between the radical sites. An important finding of this study is that the tetraradicals considered here possess singlet ground states, contrary to Hund's rule. Present findings are in close agreement with the available high-level ab initio estimates at attainable cost implying that a perturbative description of the systems is adequate. The impact of N+ on the nature of ground state for the 246-TDHP have also analyzed. The singlet-triplet energy gaps for 1245- and 1234-TDHB are smaller than for o-benzyne mainly due to the ring strain. 1235-TDHB is 14.42 and 11.05 kcal/mol lower in energy than 1245- and 1234-isomers, respectively. IVO-SSMRPT predicts 1A1-3B2 and 1A1-5B2 gaps of 25.84 and 105.15 kcal/mol, respectively for the 246-TDHP cation.
Collapse
Affiliation(s)
- Sudip Chattopadhyay
- Department of Chemistry , Indian Institute of Engineering Science and Technology , Shibpur , Howrah 711103 , India
| |
Collapse
|
9
|
Chattopadhyay S. The effect of substituents on energy splitting in organic radicals: Quantitative cognizance from ab initio studies. Chem Phys 2018. [DOI: 10.1016/j.chemphys.2018.08.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
10
|
Lischka H, Nachtigallová D, Aquino AJA, Szalay PG, Plasser F, Machado FBC, Barbatti M. Multireference Approaches for Excited States of Molecules. Chem Rev 2018; 118:7293-7361. [DOI: 10.1021/acs.chemrev.8b00244] [Citation(s) in RCA: 197] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Hans Lischka
- School of Pharmaceutical Sciences and Technology, Tianjin University, Tianjin 300072, P.R. China
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Straße 17, 1090 Vienna, Austria
| | - Dana Nachtigallová
- Institute of Organic Chemistry and Biochemistry v.v.i., The Czech Academy of Sciences, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
- Regional Centre of Advanced Technologies and Materials, Palacký University, 78371 Olomouc, Czech Republic
| | - Adélia J. A. Aquino
- School of Pharmaceutical Sciences and Technology, Tianjin University, Tianjin 300072, P.R. China
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States
- Institute for Soil Research, University of Natural Resources and Life Sciences Vienna, Peter-Jordan-Strasse 82, A-1190 Vienna, Austria
| | - Péter G. Szalay
- ELTE Eötvös Loránd University, Laboratory of Theoretical Chemistry, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary
| | - Felix Plasser
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Straße 17, 1090 Vienna, Austria
- Department of Chemistry, Loughborough University, Leicestershire LE11 3TU, United Kingdom
| | - Francisco B. C. Machado
- Departamento de Química, Instituto Tecnológico de Aeronáutica, São José dos Campos 12228-900, São Paulo, Brazil
| | | |
Collapse
|
11
|
Li C, Evangelista FA. Driven similarity renormalization group for excited states: A state-averaged perturbation theory. J Chem Phys 2018; 148:124106. [DOI: 10.1063/1.5019793] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Chenyang Li
- Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA
| | - Francesco A. Evangelista
- Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA
| |
Collapse
|
12
|
Combined complete active space configuration interaction and perturbation theory applied to conformational energy prototypes: Rotation and inversion barriers. COMPUT THEOR CHEM 2017. [DOI: 10.1016/j.comptc.2017.10.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
13
|
Sinha Ray S, Ghosh A, Shit A, Chaudhuri RK, Chattopadhyay S. A simplified ab initio treatment of diradicaloid structures produced from stretching and breaking chemical bonds. Phys Chem Chem Phys 2017; 19:22282-22301. [DOI: 10.1039/c7cp03564k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
With a proper choice of active spaces, the single root perturbation theory employing improved virtual orbitals can flawlessly describe the ground, excited, ionized, and dissociated states having varying degrees of degeneracy at the expense of low computational cost.
Collapse
Affiliation(s)
- Suvonil Sinha Ray
- Department of Chemistry
- Indian Institute of Engineering Science and Technology
- Howrah 711103
- India
| | - Anirban Ghosh
- Department of Chemistry
- Indian Institute of Engineering Science and Technology
- Howrah 711103
- India
| | | | | | - Sudip Chattopadhyay
- Department of Chemistry
- Indian Institute of Engineering Science and Technology
- Howrah 711103
- India
| |
Collapse
|