The determination of the logarithmic mean excitation energy for the stopping power of H2 with the local plasma approximation

Abstract

Abstract A statistical model based on collective modes of electronic longitudinal excitations, the local plasma approximation, is applied to the determination of the logarithmic mean excitation energy for the stopping power of chemically bound particles, viz. hydrogen molecules, in contrast to that for non-interacting particles in previous applications, by taking chemical bonding into consideration explicitly. The local electron density in H 2 required in the local plasma approximation is determined with Hartree-Fock molecular wave functions for the first time in this approximation. A value of 22.6 eV is calculated for the logarithmic mean excitation energy for the stopping power of H 2 . This value is much higher than the accepted values hitherto. The intrinsic error due to the static electron density is estimated to be 0.3 eV. However, a larger error (≈1 eV) may be possible if the uncertainties of the model are taken into consideration. Evidence is presented that a large number of data reported in the literature can be reconciled with the new high value when appropriate corrections are made.