Infrared Spectroscopy of N-Methylacetamide Revisited by ab Initio Molecular Dynamics Simulations

M P Gaigeot; R Vuilleumier; M Sprik; D Borgis

doi:10.1021/ct050029z

Infrared Spectroscopy of N-Methylacetamide Revisited by ab Initio Molecular Dynamics Simulations

J Chem Theory Comput. 2005 Sep;1(5):772-89. doi: 10.1021/ct050029z.

Authors

M P Gaigeot¹, R Vuilleumier¹, M Sprik¹, D Borgis¹

Affiliation

¹ Laboratoire de Modélisation des Systèmes Moléculaires Complexes, Université d'Evry val d'Essonne, Rue Père A. Jarland, 91025 Evry, France, Laboratoire de Physique Théorique des Liquides, Université Pierre et Marie Curie, Case Courrier 121, 4 place Jussieu, 75005 Paris, France, and Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.

PMID: 26641894
DOI: 10.1021/ct050029z

Abstract

The density functional theory based molecular dynamics simulation method ("Car-Parrinello") was applied in a numerical study of the electronic properties, hydrogen bonding, and infrared spectroscopy of the trans and cis isomer of N-methylacetamide in aqueous solution. A detailed analysis of the electronic structure of the solvated molecules, in terms of localized Wannier functions and Born atomic charges, is presented. Two schemes for the computation of the solute infrared absorption spectrum are investigated: In the first method the spectrum is determined by Fourier transforming the time correlation function of the solute dipole as determined from the Wannier function analysis. The second method uses instead the molecular current-current correlation function computed from the Born charges and atomic velocities. The resulting spectral properties of trans- and cis-NMA are carefully compared to each other and to experimental results. We find that the two solvated isomers can be clearly distinguished by their infrared spectral profile in the 1000-2000 cm(-)(1) range.