X-ray spectroscopy of blocked alanine in water solution from supermolecular and supermolecular-continuum solvation models: a first-principles study

作者：Hua Weijie; Ai Yue Jie; Gao Bin; Li Hongbao; Agren Hans; Luo Yi^*

来源：Physical Chemistry Chemical Physics, 2012, 14(27): 9666-9675.

DOI：10.1039/c2cp40732a

The N1s near-edge X-ray absorption fine structure (NEXAFS) and X-ray emission spectra (XES) of blocked alanine in water solution have been investigated at the first-principles level based on cluster models constructed from classical molecular dynamics simulations. The bulk solvent has been described by both supermolecular and combined supermolecular-continuum models. With the former model we show that NEXAFS spectra convergent with respect to system size require at least the inclusion of the second solvation shell and that averaged spectra over several hundreds of snapshots can well represent the statistical effect of different instantaneous configurations of the solvation shells. With the combined model we demonstrate that calculations of a medium-sized peptide-water supermolecule qualitatively predict the NEXAFS spectrum of the solvated peptide even considering a single geometry. Furthermore, sampling over hundreds of snapshots by the combined model, the explicit inclusion of even a few waters yields an averaged spectrum in good quantitative agreement with the discrete model results. In comparison, the XES spectra show little dependence on the structures

• 出版日期2012
• 单位中国科学技术大学