Understanding the properties of electronically excited states is a challenging task that
becomes increasingly important for numerous applications in chemistry, molecular physics …

In the past two decades, the density matrix renormalization group (DMRG) has emerged as
an innovative new method in quantum chemistry relying on a theoretical framework very …

The developments of the open-source OpenMolcas chemistry software environment since
spring 2020 are described, with a focus on novel functionalities accessible in the stable …

Psi4 is an ab initio electronic structure program providing methods such as Hartree–Fock,
density functional theory, configuration interaction, and coupled-cluster theory. The 1.1 …

We extend the recently proposed heat-bath configuration interaction (HCI) method [Holmes,
Tubman, Umrigar, J. Chem. Theory Comput. 2016, 12, 3674], by introducing a …

A formal analysis is conducted on the exactness of various forms of unitary coupled cluster
(UCC) theory based on particle-hole excitation and de-excitation operators. Both the …

We introduce a new procedure for iterative selection of determinant spaces capable of
describing highly correlated systems. This adaptive configuration interaction (ACI) …

Second-order Møller–Plesset theory (MP2) notoriously breaks down for π-driven dispersion
interactions and dative bonds in transition metal complexes. Herein, we investigate three …

We use the recently developed Heat-bath Configuration Interaction (HCI) algorithm as an
efficient active space solver to perform multiconfiguration self-consistent field calculations …

Predicting the electronic structure and properties of molecular systems that display strong
electron correlation effects continues to remain a fundamental theoretical challenge. This …