Generalized-active-space pair-density functional theory: an efficient method to study large, strongly correlated, conjugated systems

Abstract

Predicting ground- and excited-state properties of open-shell organic molecules by electronic structure theory can be challenging because an accurate treatment has to correctly describe both static and dynamic electron correlation.

Density matrix renormalization group pair-density functional theory (DMRG-PDFT): singlet–triplet gaps in polyacenes and polyacetylenes

“… a Generalized active-space pair-density functional theory with tPBE functional and 6-31G+(d,p) basis set from ref. 85. b DMRG-externally correlated multireference CI, DMRG-ec-MRCISD+Q at geometries optimized by UB3LYP/6-31G(d); see ref.…”

“…Geometries are very important for adiabatic S–T gaps. The geometries of the polyacenes for both the singlet (1 1 A g ) and triplet (1 3 B 3u ) states were taken from ref. 85.…”

OpenMolcas: From Source Code to Insight

“…MC-PDFT generally produces results that are comparable in accuracy to complete active space second-order perturbation theory (CASPT2) but at significantly lower computa-tional cost 191 for bond energies, 59,60,177,192,193 spin-multiplet splittings, [194][195][196][197] and other excitation energies. [198][199][200][201] These results are summarized in a The reference wave function is optimized from a GASSCF calculation.…”

Analytic Gradients for Complete Active Space Pair-Density Functional Theory

“…MC-PDFT has been shown to be able to predict energies with an accuracy similar to CASPT2 at a much lower computational cost. 19,20,26,[32][33][34][35][36][37] In this work, we present the formulation and first application of analytic gradients for MC-PDFT, using state-specific (SS-) CASSCF wave functions as references (SS-CAS-PDFT).…”