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Are most of the stationary points in a molecular association minima? Application of Fraga's potential to benzene–benzene
Author(s) -
Rubio Mercedes,
Torrens Francisco,
SánchezMarín José
Publication year - 1993
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.540140604
Subject(s) - maxima and minima , hessian matrix , stationary point , eigenvalues and eigenvectors , benzene , chemistry , intermolecular force , atom (system on chip) , computational chemistry , statistical physics , mathematics , molecule , physics , quantum mechanics , computer science , mathematical analysis , organic chemistry , embedded system
Abstract The importance of characterizing the stationary points of the intermolecular potential by means of Hessian eigenvalues is illustrated for the calculation of the benzene–benzene interaction using an atom‐to‐atom pair potential proposed by Fraga (FAAP). Two models, the standard one‐center‐per atom and another using three‐centers‐per atom due to Hunter and Sanders, are used to evaluate the electrostatic contributions and the results are compared. It is found in both cases that although using low‐gradient thresholds allows optimization procedures to avoid many stationary points that are not true minima computing time considerations makes the usual procedure of using high‐gradient thresholds [say, 10 −2 kj/(mol Å)] as the most efficient. Moreover, this later procedure can be recommended because the actual minima can be characterized by means of Hessian eigenvalues even if these high‐gradient thresholds are used, and further decreasing of the convergence criterion does not imply significant modifications in the geometric parameters of the minima. The possible advantages of using the three‐centers‐per‐atom model for the calculation of molecular associations between delocalized systems are also discussed on the basis of the agreement of the benzene–benzene results with experimental and theoretical data taken from the literature. © 1993 John Wiley & Sons, Inc.