Implementation of a semiclassical light-matter interaction using the Gauss-Hermite quadrature: A simple alternative to the multipole expansion

Sørensen, Lasse Kragh; Kieri, Emil; Srivastav, Shruti; Lundberg, Marcus; Lindh, Roland

doi:10.1103/physreva.99.013419

Cited by 15 publications

(32 citation statements)

References 38 publications

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“…258 Further, it shows better numerical stability with respect to the choice of basis set. 259 OpenMolcas now includes an elegant and efficient procedure using a standard Gauß-Hermite quadrature to evaluate the integrals in eq. (12) in this formalism.…”

Section: Light-matter Interaction and Beyond The Multipole Expansionmentioning

confidence: 99%

“…(12) in this formalism. 259 Both electric and magnetic terms are calculated this way, with the spin-magnetic term in eq. 13being nonzero when the spin-orbit operator in the RASSI module is used.…”

Section: Light-matter Interaction and Beyond The Multipole Expansionmentioning

confidence: 99%

“…Although no closed formula for the isotropically tensor averaged oscillator strengths is known, the exact value can be approximated by averaging over different directions using a Lebedev grid. 259,260 Although the averaging over a grid increases the computational time compared to the multipole expansion, this will only rarely affect the timing of the full electronic structure calculation.…”

Section: Light-matter Interaction and Beyond The Multipole Expansionmentioning

confidence: 99%

See 2 more Smart Citations

OpenMolcas: From Source Code to Insight

Galván

Vacher

Alavi

et al. 2019

J. Chem. Theory Comput.

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792

408

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In this article we describe the OpenMolcas environment and invite the computational chemistry community to collaborate. The open-source project already includes a large number of new developments realized during the transition from the commercial MOLCAS product to the open-source platform. The paper initially describes the technical details of the new software development platform. This is followed by brief presentations of many new methods, implementations, and features of the OpenMolcas program suite. These developments include novel wave function methods such as stochastic complete active space self-consistent field, density matrix renormalization group (DMRG) methods, and hybrid multiconfigurational

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Section: Light-matter Interaction and Beyond The Multipole Expansionmentioning

confidence: 99%

Section: Light-matter Interaction and Beyond The Multipole Expansionmentioning

confidence: 99%

Section: Light-matter Interaction and Beyond The Multipole Expansionmentioning

confidence: 99%

See 1 more Smart Citation

OpenMolcas: From Source Code to Insight

Galván

Vacher

Alavi

et al. 2019

J. Chem. Theory Comput.

Self Cite

792

408

View full text Add to dashboard Cite

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“…Transition intensities are calculated using the RAS state‐interaction (SI) approach, which also includes spin–orbit coupling . Light–matter interactions can either be calculated using the electric dipole approximation, the full second‐order expansion of the wavevector, or the exact semiclassical light–matter interaction . Calculations with RAS wavefunctions have already been used to study covalency in metal–ligand bonding, identify transient reaction intermediates in femtosecond X‐ray spectroscopy, and to assign low‐lying electronic states through their spectral fingerprints …”

Section: Introductionmentioning

confidence: 99%

Efficient calculations of a large number of highly excited states for multiconfigurational wavefunctions

et al. 2019

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Electronically excited states play important roles in many chemical reactions and spectroscopic techniques. In quantum chemistry, a common technique to solve excited states is the multiroot Davidson algorithm, but it is not designed for processes like X‐ray spectroscopy that involves hundreds of highly excited states. We show how the use of a restricted active space wavefunction together with a projection operator to remove low‐lying electronic states offers an efficient way to reach single and double‐core‐hole states. Additionally, several improvements to the stability and efficiency of the configuration interaction (CI) algorithm for a large number of states are suggested. When applied to a series of transition metal complexes the new CI algorithm does not only resolve divergence issues but also leads to typical reduction in computational time by 70%, with the largest savings for small molecules and large active spaces. Together, the projection operator and the improved CI algorithm now make it possible to simulate a wide range of single‐ and two‐photon spectroscopies. © 2019 Wiley Periodicals, Inc.

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“…Transition matrix elements up to a full second-order expansion of the wave vector have been calculated using RASSI. 46 In principle, the plane-wave form of the wave vector could also be used, [71][72][73][74] but as that operator depends on the transition energy, the cost of evaluating a scattering processes that includes tens of thousands of individual transitions becomes too high. Here K pre-edge XAS spectra have been simulated using the exact operator for comparison with the multipole expansion.…”

Section: And Si-3 (Esi †)mentioning

confidence: 99%