Henrik Koch

TL;DR: In this paper, the basis-set convergence of the electronic correlation energy in the water molecule is investigated at the second-order Mo/ller-Plesset level and at the coupled-cluster singles-and-doubles level with and without perturbative triples corrections applied.

TL;DR: In this article, the correlation-consistent polarized valence and core-valence basis sets up to sextuple zeta quality are employed to compute the correlation energies of Ne, N2, and H2O at fixed experimental geometries at the levels of second-order perturbation theory (MP2) and coupled cluster theory with singles and doubles excitations (CCSD) with a perturbative triples correction (T)).

TL;DR: In this article, an approximate coupled cluster singles and doubles model is presented, denoted CC2, where the total energy is of second-order Moller-Plesset perturbation theory (MP2) quality.

TL;DR: Dalton is a powerful general‐purpose program system for the study of molecular electronic structure at the Hartree–Fock, Kohn–Sham, multiconfigurational self‐consistent‐field, Møller–Plesset, configuration‐interaction, and coupled‐cluster levels of theory.

TL;DR: The linear and quadratic response functions have been determined for a coupled cluster reference state from the response functions, computationally tractable expressions have been derived for excitation energies, first and second-order matrix transition elements, transition matrix elements between excited states, and second and third-order frequency-dependent molecular properties as discussed by the authors.