ABINITIO SCF AND MP2 CALCULATIONS ON 4 LOW-ENERGY CONFORMERS OF N-ACETYL-N'-METHYLALANINAMIDE

In this paper we report the results of ab initio SCF calculations using the 3-21G and 6-31G** basis sets to optimize the four most important low-energy conformations of N-acetyl-N'-methylalaninamide. In addition we also report the energies for the conformers at the MP2 and SCF levels with a triple-zeta basis set, at the 6-31G** optimized geometries. We find, at the highest level of theory applied to this molecule to date, that the energy separation between the C-7 equatorial and C5 conformation is larger than previous studies have shown. Our results provide an essential set of data to calibrate molecular mechanical force fields.