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Calculation of rovibrational energy levels of diatomic molecules by Dunham method with potential obtained from ab initio calculations
Author(s) -
Mitin Alexander V.
Publication year - 1998
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/(sici)1096-987x(19980115)19:1<94::aid-jcc8>3.0.co;2-u
Subject(s) - diatomic molecule , rotational–vibrational spectroscopy , ab initio , polynomial , potential energy , solver , representation (politics) , mathematics , computational chemistry , mathematical analysis , molecule , quantum mechanics , chemistry , physics , mathematical optimization , politics , political science , law
A numerical algorithm of the Dunham method for the solution of the rovibrational Schrödinger equation is proposed. It uses a new quasi‐Hermitian method of constructing the optimal approximate polynomial for the tabularly defined potential curve of a diatomic molecule obtained from an ab initio calculation. In this method the optimal polynomial approximates the potential curve and its derivatives, but it uses only information about the potential curve for its construction. This property of the new method arises from analysis of a spectral representation of the optimal polynomial to determine how well it approximates the potential curve and its derivatives. Appropriate derivatives of the potential curve, needed in the Dunham method, are calculated by recurrence relations. Comparison with the finite‐difference method shows that the precision of both methods is similar, while the Dunham method is hundreds of times faster. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 94–101, 1998