Collect. Czech. Chem. Commun. 1980, 45, 321-329

Molecular geometries - Accuracy test of the PCILO method

Zdeněk Havlas and Petr Maloň

Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6


Applicability of the PCILO method for investigation of stationary points of the energy hypersurface has been tested with a set of 11 small organic molecules. From comparison of the molecular geometries, completely optimized with the use of the Payne algorithm, with experimental data and with the results obtained by the MINDO/3 and MNDO methods it follows that the PCILO method is suitable for semiquantitative estimate of molecular geometry (mean error in the bond length determination 5 . 10-3 nm, valence angles 3.4°). The Payne algorithm is little efficient, if the starting geometry is far from the stationary point and if the assumption of quadratic form of the hypersurface is not fulfilled.