10.1063/1.5126800">
 

Document Type

Article

Publication Date

12-17-2019

Abstract

Analytic gradients of electronic eigenvalues require one calculation per nuclear geometry, compared to at least 3n + 1 calculations for finite difference methods, where n is the number of nuclei. Analytic nonadiabatic derivative coupling terms (DCTs), which are calculated in a similar fashion, are used to remove nondiagonal contributions to the kinetic energy operator, leading to more accurate nuclear dynamics calculations than those that employ the Born-Oppenheimer approximation, i.e., that assume off-diagonal contributions are zero. The current methods and underpinnings for calculating both of these quantities, gradients and DCTs, for the State-Averaged MultiReference Configuration Interaction with Singles and Doubles (MRCI-SD) wavefunctions in COLUMBUS are reviewed. Before this work, these methods were not available for wavefunctions of a relativistic MRCI-SD Hamiltonian. Calculation of these terms is critical in successfully modeling the dynamics of systems that depend on transitions between potential energy surfaces split by the spin-orbit operator, such as diode-pumped alkali lasers. A formalism for calculating the transition density matrices and analytic derivative coupling terms for such systems is presented.

Comments

© 2019 Authors, published under an exclusive license with American Institute of Physics.

AFIT Scholar, as the repository of the Air Force Institute of Technology, furnishes the published Version of Record for this article in accordance with the sharing policy of the publisher, AIP Publishing. A 12-month embargo was observed.

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in volume 151 of Journal of Chemical Physics as cited below and may be found at the DOI link on this page.

Funding note: "We would like to acknowledge the High-Energy Laser Joint Technology Office, Albuquerque, NM, for their financial support of this effort."

Source Publication

Journal of Chemical Physics

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