Edward T. Seidl

TL;DR: The Psi4 program is a new approach to modern quantum chemistry, encompassing Hartree–Fock and density‐functional theory to configuration interaction and coupled cluster and offers flexible user input built on the Python scripting language that enables both new and experienced users to make full use of the program's capabilities.

TL;DR: PSI3 as discussed by the authors is a program system and development platform for ab initio molecular electronic structure computations, which includes mature programming interfaces for parsing user input, accessing commonly used data such as basis-set information or molecular orbital coefficients, and retrieving and storing binary data, especially multi-index quantities such as electron repulsion integrals.

TL;DR: In this article, the global minimum on the water trimer potential energy surface has been investigated by means of second-order Mo/ller-Plesset (MP2) perturbation theory employing the series of correlation-consistent basis sets aug-cc-pVXZ (X = D, T, Q, 5, 6), the largest of which contains 1329 basis functions.

TL;DR: In this article, the transition state for cyclo-O4 dissociation to two O2 molecules has been located at a number of levels of theory using a double zeta plus polarization (DZP) basis set.

TL;DR: In this article, an analogy is constructed between the known composition of elemental sulfur (principally S8 rings) and the unknown oxygen rings, and both self-consistent field and configuration interaction including single and double excitations (CISD) methods have been employed in conjunction with double zeta plus polarization basis sets.