PHYSICAL
AND BIOPHYSICAL CHEMISTRY DIVISION
COMMISSION ON MOLECULAR STRUCTURE AND SPECTROSCOPY
Quantum chemical B3LYP/cc-pvqz computation of ground-state structures
and properties of small molecules with atoms of Z
£ 18 (hydrogen to argon) (IUPAC Technical Report)
Rudolf Janoschek
Institut für Theoretische Chemie, Karl-Franzens-Universität
Graz, Strassoldogasse 10 A-8010 Graz, Austria
Abstract: Since density functional theory (DFT) achieved a remarkable
break-through in computational chemistry, the important general question
"How reliable are quantum chemical calculations for spectroscopic
properties?" should be answered anew. In this project, the most
successful density functionals, namely the Becke B3LYP functionals,
and the correlation-consistent polarized valence quadruple zeta basis
sets (cc-pvqz) are applied to small molecules. In particular, the complete
set of experimentally known diatomic molecules formed by the atoms H
to Ar (these are 214 species) is uniformly calculated, and calculated
spectroscopic properties are compared with experimental ones. Computationally
demanding molecules, such as open-shell systems, anions, or noble gas
compounds, are included in this study. Investigated spectroscopic properties
are spectroscopic ground state, equilibrium internuclear distance, harmonic
vibrational wavenumber, anharmonicity, vibrational absolute absorption
intensity, electric dipole moment, ionization potential, and dissociation
energy. The same computational method has also been applied to the ground-state
geometries of 56 polyatomic molecules up to the size of benzene. Special
sections are dedicated to nuclear magnetic resonance (NMR) chemical
shifts and isotropic hyperfine coupling constants. Each set of systems
for a chosen property is statistically analyzed, and the above important
question "How reliable...?" is mathematically answered by
the mean absolute deviation between calculated and experimental data,
as well as by the worst agreement. In addition to presentation of numerous
quantum chemically calculated spectroscopic properties, a corresponding
updated list of references for experimentally determined properties
is presented.
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file - 357 KB]
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