Premium
Assessing Spin‐Component‐Scaled Second‐Order Møller–Plesset Theory Using Anharmonic Frequencies
Author(s) -
Domin Dominik,
Benoit David M.
Publication year - 2011
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201100499
Subject(s) - diatomic molecule , anharmonicity , ab initio , component (thermodynamics) , spin (aerodynamics) , møller–plesset perturbation theory , physics , scaling , atomic physics , molecule , molecular physics , chemistry , quantum mechanics , thermodynamics , perturbation theory (quantum mechanics) , mathematics , geometry
Four common parametrisations of spin‐component‐scaled second‐order Møller–Plesset (MP2) theory are benchmarked by calculating the anharmonic vibrational frequencies of a test suite consisting of eighteen diatomic and five small molecules. Of the four methods, the scaled opposite‐spin MP2 (SOS‐MP2), the variable‐scaling opposite‐spin MP2 (VOS‐MP2) and the spin‐component‐scaled MP2 (SCS‐MP2) methods perform statistically better than standard MP2 theory, while the spin‐component scaled for nucleic bases MP2 (SCSN‐MP2) performs worse. Vibrations of closed‐shell diatomic molecules are slightly more accurately described by the SOS‐MP2 method of Head‐Gordon ( ε MAD =51 cm −1 ) than the SCS‐MP2 method of Grimme ( ε MAD =61 cm −1 ) or the size‐consistent parametrisation of VOS‐MP2 ( ε MAD =54 cm −1 ). For open‐shell diatomic molecules, the SOS‐MP2 ( ε MAD =83 cm −1 ) and SCS‐MP2 ( ε MAD =81 cm −1 ) methods are of similar accuracy, while VOS‐MP2 is slightly better ( ε MAD =77 cm −1 ). Since the VOS‐MP2 and SOS‐MP2 methods tend to have smaller deviations from experiment, and they can be made computationally more economical than the SCS‐MP2 or MP2 methods, we suggest that they should be the preferred ab initio method for computing vibrational frequencies in large molecules.