Excited state meanfield theory without automatic differentiation
Abstract
We present a formulation of excited state meanfield theory in which the derivatives with respect to the wave function parameters needed for wave function optimization (not to be confused with nuclear derivatives) are expressed analytically in terms of a collection of Focklike matrices. By avoiding the use of automatic differentiation and grouping Fock builds together, we find that the number of times we must access the memoryintensive twoelectron integrals can be greatly reduced. Furthermore, the new formulation allows the theory to exploit the existing strategies for efficient Fock matrix construction. We demonstrate this advantage explicitly via the shellpair screening strategy with which we achieve a cubic overall cost scaling. Using this more efficient implementation, we also examine the theory's ability to predict charge redistribution during charge transfer excitations. Using the coupled cluster as a benchmark, we find that by capturing orbital relaxation effects and avoiding selfinteraction errors, excited state mean field theory outperforms other lowcost methods when predicting the charge density changes of charge transfer excitations.
 Publication:

Journal of Chemical Physics
 Pub Date:
 May 2020
 DOI:
 10.1063/5.0003438
 arXiv:
 arXiv:2002.00322
 Bibcode:
 2020JChPh.152t4112Z
 Keywords:

 Physics  Chemical Physics;
 Condensed Matter  Strongly Correlated Electrons
 EPrint:
 doi:10.1063/5.0003438