Electron Chirality in Amino Acid Molecules

We evaluated the total electron chirality in alanine, serine, and valine, which are molecules that have chiral structures. Previously, it has been considered that the total electron chirality of molecules composed of only light elements cannot be computed within usual computational conditions of relativistic four-component wave functions. In this work, it is shown that the total electron chirality can be calculated if some diffuse functions are added to Gaussian basis sets. This is demonstrated for the H$_2$O$_2$ molecule. By adding diffuse Gaussian functions to basis sets, the total electron chirality of L-alanine, L-serine, and L-valine are evaluated. It is also shown that the total electron chirality is derived by the cancellation between large contributions from each orbital, and the total electron chirality in excited and ionized states is expected to be much larger than that of the ground state.