Are most of the stationary points in a molecular association minima? Application of Fraga's potential to benzene–benzene
✍ Scribed by Mercedes Rubio; Francisco Torrens; José Sánchez-Marín
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 876 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0192-8651
No coin nor oath required. For personal study only.
✦ Synopsis
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 threecenters-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, kJ/(mol A)] 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. 6 1993 by John Wiley & Sons, Inc.