Theoretical study of the X-ray natural circular dichroism of some crystalline amino acids

- Theoretical procedure of XNCD spectra was developed with DFT.
- XNCD spectra of alanine and serine were calculated.
- Cluster models representing the solid phase were also applied.

X-ray natural circular dichroism (XNCD) spectra of alanine and serine were calculated at the C, N, and O K-edges within the framework of density functional theory. Basis set and gauge dependence of d-alanine were examined as a test case. XNCD spectra of crystalline d-alanine and l-serine were obtained using cluster models of increasing size. The absolute intensities of the XNCD spectra were found to be reduced in the solid phase compared to the gas phase monomers, suggesting that a monomer model is not necessarily a good representation of the solid phase.