The discussion on the Potential Distribution Analysis (PED) and internal coordinate definitions are presented. The VEDA program written by the author, reads the input data automatically from the Gaussian program output files. Then, VEDA automatically proposes an introductory set of local mode coordinates. Next, the more adequate coordinates are proposed by the program and optimized to obtain maximal elements of each column (internal coordinate) of the PED matrix. In that way the theoretical spectrum become understandable in category of chemical structure elements: skeleton, bonding and functional groups. The final goal of the proper representation of the theoretical vibrational spectra is always to give possibility of the most accurate interpretation of the experimental spectra, what gives the chemist the desired knowledge. As VEDA program can manage with over 200 atoms – it can be useful for peptides/proteins spectra elucidation.
Author(s): Michal H. Jamroz