Density matrix embedding theory (DMET) has been demonstrated as a promising wave function-in-wave function embedding method to treat electron correlation for large and extended systems. The success of DMET lies in the fact that any large system can be partitioned into small fragments, thus they can be affordably treated by highly accurate quantum-chemical solvers, such as density matrix renormalization group, full configuration interaction, complete active space self-consistent field, couple cluster theory, etc. The extension of DMET to periodic system has been formulated to compute electron correlation energy in realistic solids. Despite of gaining some successes, the current formalism has its root in one-shot DMET where the approximate bath orbitals constructed from a Hartree-Fock wave function are not optimized in a self-consistent manner as being exploited in the DMET formalism for molecular systems, thereby hindering its application to strongly correlated systems. In this work, we present an extension of self-consistent DMET to periodic systems via a k-point independent approximation for the correlation potential. Following the previous work, a unit cell, defined as the reference unit cell, is treated as an impurity embedded in the environment made up by surrounding unit cells. The embedding is carried out for the real-space presentation of the wave function using the Wannier functions. The k-point independent correlation potential is included in the momentum space one-electron Hamiltonian and it is self-consistently optimized to reduce the difference between the one-body density matrix of the reference unit cell at the mean-field level and that at the high-level. Different quantum-chemical methods are employed as the impurity solver to establish a hierarchy of wave function theory for solid-state calculation. We benchmark the performance of the proposed method for real solids, such as a hydrogen molecule in a box, silicon and diamond crystals. Our theory can be applied to compute ground state energy as well as electronic band structure for periodic systems.

Multiconfigurational wave function methods for periodic systems via density matrix embedding theory

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.