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Fundamental vibrational frequencies and dominant resonances in methylamine isotopologues by ab initio and density functional theory methods
Author(s) -
Levi Chen,
Martin Jan M. L.,
Bar Ilana
Publication year - 2008
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.20885
Subject(s) - anharmonicity , isotopologue , density functional theory , ab initio , ab initio quantum chemistry methods , coupled cluster , methylamine , atomic physics , harmonic , chemistry , molecular physics , physics , computational chemistry , quantum mechanics , molecule , organic chemistry
Ab initio and density functional theory (DFT) calculations were performed for obtaining fundamental vibrational frequencies of methylamine, CH 3 NH 2 , and its deuterated variants CH 3 ND 2 , CD 3 NH 2 , and CD 3 ND 2 . The calculations were carried out using the CCSD(T) coupled cluster approximation with cc‐pVTZ and cc‐pVQZ basis sets, and by the DFT method with the semiempirical hybrid functional B97‐1 with polarization consistent pc‐2 and pc‐3 basis sets. Reasonable performance of the DFT harmonic and ab initio harmonic calculations was found, which improved considerably upon combination of the harmonic fundamental frequencies with anharmonic corrections from the smaller, pc‐2, basis. The computed anharmonic fundamental frequencies of methylamine isotopologues agree very well with the experimental values and represent a useful tool for assignment and analysis of the dominant resonances. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008