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 …

A series of methods (SDSCI, SDSPT2, iCI, iCIPT2, iCISCF (2), iVI, and iCAS) is introduced to
accurately describe strongly correlated systems of electrons. Born from the (restricted) static …

We introduce the atomic valence active space (AVAS), a simple and well-defined automated
technique for constructing active orbital spaces for use in multiconfiguration and …

We extend our recently developed heat-bath configuration interaction (HCI) algorithm, and
our semistochastic algorithm for performing multireference perturbation theory, to calculate …

Even when starting with very poor initial guess, the iterative configuration interaction (iCI)
approach [J. Chem. Theory Comput. 12, 1169 (2016)] for strongly correlated electrons can …

The electronically excited states of methylene (CH2), ethylene (C2H4), butadiene (C4H6),
hexatriene (C6H8), and ozone (O3) have long proven challenging due to their complex …

We introduce and analyze various approaches for computing excited electronic states using
our recently developed adaptive configuration interaction (ACI) method [Schriber, JB and …

The incremental expansion provides a polynomial scaling method for computing electronic
correlation energies. This article details a new algorithm and implementation for the …

We present a Perspective on what the future holds for full configuration interaction (FCI)
theory, with an emphasis on conceptual rather than technical details. Upon revisiting the …

Full configuration interaction (FCI) can provide an exact molecular ground-state energy
within a given basis set and serve as a benchmark for approximate methods in quantum …