Locally coupled open subsystems: A formalism for affordable electronic structure calculations featuring fractional charges and size consistency
Abstract
This manuscript introduces a methodology (within the Born-Oppenheimer picture) to compute electronic ground-state properties of molecules and solids/surfaces with fractionally occupied components. Given a user-defined division of the molecule into subsystems, our theory uses an auxiliary global Hamiltonian that is defined as the sum of subsystem Hamiltonians, plus the spatial integral of a second-quantized local operator that allows the electrons to be transferred between subsystems. This electron transfer operator depends on a local potential that can be determined using density functional approximations and/or other techniques such as machine learning. The present framework employs superpositions of tensor-product wave functions, which can satisfy size consistency and avoid spurious fractional charges at large bond distances. The electronic population of each subsystem is in general a positive real number and is obtained from wave-function amplitudes, which are calculated by means of ground-state matrix diagonalization (or matrix propagation in the time-dependent case). Our method can provide pathways to explore charge-transfer effects in environments where dividing the molecule into subsystems is convenient and to develop computationally affordable electronic structure algorithms.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jul 19, 2018
- Source ID
- 10.1063/1.5038557
Entities
People
- George C. Schatz
- Mark Ratner
- MartÃn A Mosquera
Organizations
- Air Force Office of Scientific Research
- Northwestern University
- United States Department of Energy