Methanol: A critical test of intensity models for molecular soft X-ray emission

Abstract

We have used methanol as a critical test case for calculations of molecular soft X-ray emission spectra. Energies and intensities calculated from self-consistent multi-configurational wavefunctions optimized for each separate state have been used to theoretically analyze the emission spectra via the evaluation of dipole electronic transitions at different levels of approximation. The one-center intensity model is found to describe the X-ray intensities of methanol well. Results confirm that for main soft X-ray transitions the largest correction to the one-center model is given by the relaxation effect, while the effect of correlation does not change the overall results from ΔSCF calculations to any appreciable extent. A previously known ambiguity concerning the two outermost bands in the carbon spectrum is investigated here although the present results do not conclusively explain the discrepancy between the theoretical intensities corresponding to these transitions and the experimental data.