Variational Principles in Quantum Monte Carlo: The Troubled Story of Variance Minimization.

ABSTRACT: We investigate the use of different variational principles in quantum Monte Carlo, namely, energy and variance minimization, prompted by the interest in the robust and accurate estimation of electronic excited states. For two prototypical, challenging molecules, we readily reach the accuracy of the best available reference excitation energies using energy minimization in a state-specific or state-average fashion for states of different or equal symmetry, respectively. On the other hand, in variance minimization, where the use of suitable functionals is expected to target specific states regardless of the symmetry, we encounter severe problems for a variety of wave functions: as the variance converges, the energy drifts away from that of the selected state. This unexpected behavior is somet

SUBMITTER: Cuzzocrea A 

PROVIDER: S-EPMC7365558 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature