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Shape description of conformationally flexible molecules: Application to two‐dimensional conformational problems
Author(s) -
Arteca Gustavo A.,
Mezey Paul G.
Publication year - 1988
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560340706
Subject(s) - van der waals force , chemistry , molecule , molecular geometry , surface (topology) , ab initio , chemical physics , computational chemistry , topology (electrical circuits) , geometry , mathematics , organic chemistry , combinatorics
Nuclear configuration and molecular shape are two different concepts. The former refers to the geometry of the nuclear framework, whereas the shape of a molecule is better represented by a molecular envelope surface enclosing the nuclei. Nevertheless, there exist relationships between the molecular shape and the conformational arrangements of the nuclei. For certain changes in the nuclear geometry, the shape of a molecular surface does not change significantly, whereas for some others it may undergo essential topological changes. The characterization and interrelations of these changes provide a rigorous classification of reaction paths and conformational rearrangements for flexible molecules in terms of shape features. In this article we use a recently introduced topological tool to study molecular shape and molecular conformations: the “shape groups” (symmetry‐independent homology groups) of a molecule. Van der Waals surfaces are considered as illustrative examples of molecular surfaces. We study the changes in the shape of van der Waals surfaces of hydroquinone, resorcinol, and catechol for a number of two‐dimensional conformational problems, where the nonrigid conformational paths have been calculated at the STO −3 G ab initio Hartree–Fock level.