Modern vibrational spectroscopy is more than just an analytical tool. Information about the
electronic structure of a molecule, the strength of its bonds, and its conformational flexibility …

An up-to-date overview of the CFOUR program system is given. After providing a brief
outline of the evolution of the program since its inception in 1989, a comprehensive …

Cosmic evolution is the tale of progressive transition from simplicity to complexity. The
newborn universe starts with the simplest atoms formed after the Big Bang and proceeds …

This article primarily discusses the utility of vibrational perturbation theory for the prediction
of X–H stretching vibrations with particular focus on the specific variant, second-order …

The aim of this paper is 2-fold. First, we want to report the extension of our virtual
multifrequency spectrometer (VMS) to anharmonic intensities for Raman optical activity …

Vibrational levels of polyatomic molecules are analysed with Van Vleck perturbation theory
to connect experimental energy levels to computed molecular potential energy surfaces …

The second-order vibrational Hamiltonian of a semi-rigid polyatomic molecule when
resonances are present can be reduced to a quasi-diagonal form using second-order …

Anharmonic vibrational states of semirigid polyatomic molecules are often studied using the
second-order vibrational perturbation theory (VPT2). For efficient higher-order analysis, an …

A derivation of fourth-order vibrational perturbation theory (VPT4) based on the Watson
Hamiltonian in dimensionless rectilinear normal coordinates is presented. Terms that are …

Geometric energy derivatives which rely on core-corrected focal-point energies extrapolated
to the complete basis set (CBS) limit of coupled cluster theory with iterative and noniterative …