Ab initio and molecular mechanics conformational analysis of neutral L-proline

The energetically low-lying parts of the potential energy surface of L-proline were investigated by ab initio (RHF/6-311 + + G**) calculations. The results are discussed with respect to the parametrization of the MM3 force field and in comparison with those obtained earlier for glycine and α-alanine, on the one hand, and for N-acetyl-L-proline amide, on the other hand.