Ground and excited state <scp>CASPT</scp>2 geometry optimizations of small organic molecules

Page, Christopher; Olivucci, Massimo

doi:10.1002/jcc.10145

Cited by 134 publications

(220 citation statements)

References 24 publications

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“…To summarise, the CASSCF results are in very good agreement with the geometries given in the supplementary material of Ref. [7], with errors for bond lengths and angles within 0.001 Å and 0.1°, respectively. Larger deviations are seen for the CASPT2 results, with some errors of the order of 0.01 Å /1.0°.…”

Section: Ab Initio Calculationssupporting

confidence: 74%

“…Following Page and Olivucci [7], we have used the 6-31G(d) basis set. In our calculations cartesian basis functions were employed.…”

Section: Ab Initio Calculationsmentioning

confidence: 99%

“…Again following Ref. [7], the active space was selected to include the six p-valence molecular orbitals. C s symmetry was enforced for the planar optimisations.…”

Section: Ab Initio Calculationsmentioning

confidence: 99%

“…We attribute these discrepancies to the different implementation of CASPT2 gradients used in Ref. [7], namely numerical gradients derived from MOLCAS energies.…”

Section: Ab Initio Calculationsmentioning

confidence: 99%

“…At the higher CASPT2 level of theory, Page and Olivucci [7] have shown that the PSB3 S 1 potential energy surface is qualitatively different from CASSCF, with only a single planar cis CASPT2 minimum compared to two for CASSCF. However, CASPT2 gradient calculations are computationally too expensive to scale up to the full Dedicated to Professor Santiago Olivella on the occasion of his 65th birthday and published as part of the Olivella Festschrift Issue.…”

Section: Introductionmentioning

confidence: 99%

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Assessment of semiempirical methods for the photoisomerisation of a protonated Schiff base

2009

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The potential energy surfaces and non-adiabatic dynamics of the C 5 H 6 NH 2 ? protonated Schiff base (PSB3) have been investigated using the OM2 semiempirical Hamiltonian with GUGA configuration interaction. Three approaches to selecting the GUGA-CI active space are evaluated using closed-shell and open-shell molecular orbitals. Energy minima and minimum energy crossing points (MECPs) have been compared with ab initio CASSCF and CASPT2 results. Only the open-shell calculations give a qualitatively correct MECP. Minimum energy path (MEP) calculations demonstrate that a minimal active space gives a barrierless path from the planar S 1 minimum to the ground state, whereas larger active spaces result in a small barrier to torsional motion. Surface hopping dynamics calculations indicate that this barrier induces bi-exponential dynamics. The comparable CAS-SCF S 1 energy surface is barrierless, but the CASPT2 surface features an energy plateau, which may also lead to more complex dynamics.

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Section: Ab Initio Calculationssupporting

confidence: 74%

“…Following Page and Olivucci [7], we have used the 6-31G(d) basis set. In our calculations cartesian basis functions were employed.…”

Section: Ab Initio Calculationsmentioning

confidence: 99%

“…Again following Ref. [7], the active space was selected to include the six p-valence molecular orbitals. C s symmetry was enforced for the planar optimisations.…”

Section: Ab Initio Calculationsmentioning

confidence: 99%

“…We attribute these discrepancies to the different implementation of CASPT2 gradients used in Ref. [7], namely numerical gradients derived from MOLCAS energies.…”

Section: Ab Initio Calculationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Assessment of semiempirical methods for the photoisomerisation of a protonated Schiff base

2009

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Spectroscopy: Applications

Serrano-Andr��s¹,

Merch��n²

1998

Encyclopedia of Computational Chemistry

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Recent years have seen an extraordinary development in the applicability and accuracy of ab initio methods to compute molecular excited states, which are now generally determined with a precision of 0.1–0.2 eV. The size and character of the problems have increased to make the calculations competitive and complementary to the experimental determinations involving medium and large molecular systems. Many examples can be provided of this new era in the quantum chemistry of the excited state where the multiconfigurational methods, in particular, CASPT2, have been the main protagonists. The present article contains an account of the types and nature of excited states, a compilation of methods, strategies, and problems to be solved in the calculation of molecular excited states, particularly to obtain electronic transition energies and properties, such as band intensities and state lifetimes. Finally, a number of examples and achievements in the field give an overall view of what can be computed nowadays and how the computations can be performed. Illustrative examples include the calculation of dark states, vibrational resolution of electronic bands, novel assignments, interplay between theoretical spectroscopy and experiment, and adiabatic and nonadiabatic photochemical processes.

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25th Anniversary Article: Design of Polymethine Dyes for All‐Optical Switching Applications: Guidance from Theoretical and Computational Studies

et al. 2013

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All-optical switching--controlling light with light--has the potential to meet the ever-increasing demand for data transmission bandwidth. The development of organic π-conjugated molecular materials with the requisite properties for all-optical switching applications has long proven to be a significant challenge. However, recent advances demonstrate that polymethine dyes have the potential to meet the necessary requirements. In this review, we explore the theoretical underpinnings that guide the design of π-conjugated materials for all-optical switching applications. We underline, from a computational chemistry standpoint, the relationships among chemical structure, electronic structure, and optical properties that make polymethines such promising materials.

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Ground and excited state CASPT2 geometry optimizations of small organic molecules

Cited by 134 publications

References 24 publications

Assessment of semiempirical methods for the photoisomerisation of a protonated Schiff base

Assessment of semiempirical methods for the photoisomerisation of a protonated Schiff base

Spectroscopy: Applications

25th Anniversary Article: Design of Polymethine Dyes for All‐Optical Switching Applications: Guidance from Theoretical and Computational Studies

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