The Piris natural orbital functional (PNOF) based on a new approach for the two-electron cumulant has been used to predict adiabatic ionization potentials, equilibrium bond distances, and harmonic vibrational frequencies of 18 diatomic molecules. Vertical ionization potentials have been calculated for the same set of diatomic molecules and another set of 20 polyatomic molecules using energy-dif...

The recent work of the authors' group in the field of KEMS studies of intermetallic gaseous molecules is reviewed. Examples are given of systems such as intragroup 14 diatomic molecules, -triand tetratomic species in the SiSn systems, and diatomic species containing Group 11 elements. Special attention is given to species containing heavy metals, where relativistic effects can play an important...