THE DETERMINATION OF ENERGY BY AB INITIO METHODS: ESTIMATION OF ERRORS AND SOME IMPROVEMENTS

Abstract

This work presents a statistical analysis of errors in the ab initio determination of molecular energy. These sets of analyses have allowed us to separate the errors in systematic and random components and also to realize that differences between experimental data and theoretical calculations are larger than those initially suspected. Although there is a limit to how small this difference can be analyzed by our methods, procedures to improve ab initio molecular energies are proposed. This has been achieved by reducing the systematic error obtained by correlating the calculated results to the most accurate data (in this case CCSD (T)), as well as by reducing the random error by mixing the results of different standard procedures.