Analytic gradients for compressed multistate pair-density functional theory. (18th October 2022)

• Record Type: Journal Article
• Authors: Bao, Jie J.; Hermes, Matthew R.; Scott, Thais R.; Sand, Andrew M.; Lindh, Roland; Gagliardi, Laura; Truhlar, Donald G.
• Is Part Of: Molecular physics. Volume 120:Number 19/20(2022)
• Publication Date: 2022-10-18
• Subjects: Analytic gradients -- pair-density functional theory -- electronic structure method -- molecular geometry -- excited states; Molecules -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Molécules -- Périodiques; Chimie physique et théorique -- Périodiques; 539.6.05
• DOI: 10.1080/00268976.2022.2110534
• Languages: English
• ISSNs: 0026-8976

Abstract

Abstract : Photochemical reactions often involve states that are closely coupled due to near degeneracies, for example by proximity to conical intersections. Therefore, a multistate method is used to accurately describe these states; for example, ordinary perturbation theory is replaced by quasidegenerate perturbation theory. Multiconfiguration pair-density functional theory (MC-PDFT) provides an efficient way to approximate the full dynamical correlation energy of strongly correlated systems, and we recently proposed compressed multistate pair-density functional theory (CMS-PDFT) to treat closely coupled states. In the present paper, we report the implementation of analytic gradients for CMS-PDFT in both OpenMolcas and PySCF, and we illustrate the use of these gradients by applying the method to the excited states of formaldehyde and phenol. GRAPHICAL ABSTRACT: UF0001