Multiconfiguration Pair-Density Functional Theory for Strongly Correlated Systems*

An overview of recent developments in multiconfiguration pair-density functional theory (MC-PDFT) will be presented, with special emphasis on linearized PDFT (L-PDFT).[1]

The method involves the construction of an effective L-PDFT Hamiltonian operator, achieved by expanding the MC-PDFT energy expression to first-order in a Taylor series of the wave function density. This approach allows for the accurate prediction of potential energy surface topologies near conical intersections and locally avoided crossings, even in challenging cases like phenol, methylamine, and the spiro cation.

Additionally, we will introduce quantum embedding and localization methods tailored to characterize systems ranging from extended, strongly correlated molecules to periodic systems. We will present the integration of quantum embedding with MC-PDFT, utilizing densities derived from periodic density matrix embedding theory.[2] Our discussion will feature examples of calculations related to local excitations within both solid-state materials and molecules.

 

[1] Hennefarth, M. Hermes, D. Truhlar, and L. Gagliardi, Linearized Pair-Density Functional Theory, J. Chem. Theory Comput., 2023, 19, 3172–3183 DOI: 10.1021/acs.jctc.3c00207

[2] A. Mitra, M. Hermes, and L. Gagliardi, Density Matrix Embedding Using Multiconfiguration Pair-Density Functional Theory, J. Chem. Theory Comput., 2023, 19, 3498–3508 DOI: https://doi.org/10.1021/acs.jctc.3c00247