Localized molecular orbital studies in momentum space. I. compton profiles of 1s core electrons and hydrocarbons

The calculations of momentum space properties for the polyatomic molecules CH₄, C₂H₄ and C₂H₆ using localized molecular orbitals of double zeta quality basis sets are presented. The LMO analysis shows that localized and canonical core electrons have different momentum space properties, and that in agreement with the experimental data of Eisenberger and Marra one can distinguish the momentum properties of the CC single and double bonds. The effect of environment on a bond is seen by comparing the CH bond in these three molecules.The concept of electron pair size is introduced as a quantitative guide for interpreting momentun space properties.