Combining relativistic quantum-chemistry theories and electron-momentum spectroscopy to study valence-electron structures of molecules

Abstract

We report the combination of the Amsterdam density-functional relativistic quantum-chemistry program and electron-momentum spectroscopy to interpret electronic structures of molecules. We calculate momentum profiles of molecular orbital using the two-component relativistic theory. The momentum profiles of the complete valence shell orbitals of ${\text{I}}_{2}$ and ${\text{Au}}_{2}$ molecules are obtained in comparison between the nonrelativistic and relativistic calculations. The theoretical results show that relativistic effects have significant influences on the momentum distributions for valence orbitals of ${\text{I}}_{2}$ and ${\text{Au}}_{2}$. In order to verify the validity of the calculations, the high-resolution experimental momentum distributions of the $5{P}_{3/2}$ and $5{P}_{1/2}$ states of xenon are presented in comparison with relativistic quantum-chemistry theories.