Article on DMRG-PDFT selected for Chemical Science 'best of' collection

Chemical Science has selected the article, “Density Matrix Renormalization Group Pair-Density Functional Theory (DMRG-PDFT): Singlet-Triplet Gaps in Polyacenes and Polyacetylenes," for its themed collection, Most Popular 2018-2019 Physical and Theoretical Chemistry Articles.

This article was written by Prachi Sharma, Varinia Bernales, Ph.D., Regents Professor Donald Truhlar, Professor Laura Gagliardi, and Stefan Knecht, Ph.D., from the Laboratory of Physical Chemistry, ETH Zürich

According to the abstract for the article: "The density matrix renormalization group (DMRG) is a powerful method to treat static correlation. Here we present an inexpensive way to calculate correlation energy starting from a DMRG wave function using pair-density functional theory (PDFT). We applied this new approach, called DMRG-PDFT, to study singlet–triplet gaps in polyacenes and polyacetylenes that require active spaces larger than the feasibility limit of the conventional complete active-space self-consistent field (CASSCF) method. The results match reasonably well with the most reliable literature values and have only a moderate dependence on the compression of the initial DMRG wave function. Furthermore, DMRG-PDFT is significantly less expensive than other commonly applied ways of adding additional correlation to DMRG, such as DMRG followed by multireference perturbation theory or multireference configuration interaction."