ESCA: Chemical shifts of K-shell electron binding energies for first-row atoms in molecules

Chemical shifts of K-shell electron binding energies for first-row atoms in molecules due to their different chemical environments have been obtained from double-zeta basis SCF-MO calculated ground state 1s orbital energies using Koopman's theorem. This computational procedure is valid because it is known that the energy quantities neglected thereby are either approximately invariant for a given atom, or small. The calculated chemical shifts are characteristic of an atom in a functional group, show a linear relationship with net charge, and agree with experimental numbers in the few cases where comparison is possible.