Structures and harmonic vibrational frequencies for excited states of diatomic molecules with CCSD(R12) and CCSD(F12) models.

NonCommercial-NoDerivatives 4.0 International License. Structures and harmonic vibrational frequencies for excited states of diatomic molecules with CCSD(R12) and CCSD(F12) models

Highly accurate CCSD(R12) and CCSD(F12) optical response properties using standard triple-zeta basis sets.

Coupled-cluster response theory for frequency-dependent optical properties within the coupled-cluster singles-and-doubles model (CCSD) has been derived and implemented for ansatz 2 of the explicitly correlated CCSD(R12) and CCSD(F12) methods as part of the program package DALTON. The basis set convergence of static dipole moments, polarizabilities, and parallel averages of first and second hype...

Theoretical spectroscopic characterization at low temperatures of detectable sulfur-organic compounds: ethyl mercaptan and dimethyl sulfide.

Highly correlated ab initio methods are used for the spectroscopic characterization of ethyl mercaptan (CH3CH2 (32)SH, ETSH) and dimethyl sulfide (CH3 (32)SCH3, DMS), considering them on the vibrational ground and excited torsional states. Since both molecules show non-rigid properties, torsional energy barriers and splittings are provided. Equilibrium geometries and the corresponding rotationa...

Density functional theory predictions of anharmonicity and spectroscopic constants for diatomic molecules

The reliability of density functional theory and other electronic structure methods is examined for anharmonicities and spectroscopic constants of the ground electronic states of several diatomic molecules. The equilibrium bond length re , harmonic vibrational frequency ve , vibrational anharmonicity vexe , rotational constant Be , centrifugal distortion constant D̄e , and vibration-rotation int...

XH-stretching overtone transitions calculated using explicitly correlated coupled cluster methods.

We have calculated XH-stretching (where X=O, C, F, Cl) fundamental and overtone transitions for three diatomics and a few small molecules using a local mode model. The potential energy curves and dipole moment functions are calculated using the recently developed explicitly correlated coupled cluster with single doubles and perturbative triples theory [CCSD(T)-F12] with the associated VXZ-F12 (...