Torsional motions of methyl and ammonium groups in the L-alanine crystal : a comparison of molecular dynamics and normal mode calculationsJ Garen, MJ Field, G Kneller, M Karplus and J SmithJ. Chim. Phys., 88 (1991) 2587-2596DOI: https://doi.org/10.1051/jcp/1991882587