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Analytical energy derivatives and normal modes in force fields employing lone‐pair pseudoatoms
Author(s) -
Waldman Marvin,
Masek Brian B.
Publication year - 1989
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.540100608
Subject(s) - lone pair , force field (fiction) , field (mathematics) , computational chemistry , potential energy , classical mechanics , physics , chemistry , mathematics , quantum mechanics , molecule , pure mathematics
Formulas are derived for analytical first and second energy derivatives with respect to nuclear coordinates in molecular mechanics force fields employing lone‐pair pseudoatoms. These derivatives may further be used for the calculation of normal modes and vibrational frequencies while properly accounting for the presence of pseudoatoms. The equations are applied using the MM 2 force field to calculate the vibrational spectrum of methanol to illustrate the applicability of the method. The results are compared to both experiment and a numerical approximation in which small masses are assigned to the lone‐pair pseudoatoms.