Relativistic Change in Bond Overlap Population for the Study of Relativistic Effects on Bond Length of Diatomic Molecules

Abstract

Bond overlap population has been applied to study the relativistic effects (contraction or expansion) on the bond length of CuH and AuH diatomic hydride molecules, using the nonrelativistic and relativistic DV-Xα molecular orbital methods. The relativistic bond length changes are estimated by comparing the dependence of the nonrelativistic and relativistic bond overlap population on the interatomic distance. The results thus obtained for the diatomic molecules are in good agreement with those estimated with the bonding energy calculations. The similar approach has been applied to the Au 2 and Pb 2 diatomic molecules. We have found that the positive and negative signs of the relativistic change in the bond overlap population at an experimentally determined bond length are useful to estimate whether the bond length is relativistically contracted or expanded.