Aqueous solvation of an amide molecule from first principles molecular simulations: Structure, hydrogen bond dynamics and spectral signature

Density functional theory (DFT) based Car–Parrinello molecular dynamics (CPMD) simulations were carried out to investigate the structure and dynamics of aqueous solvation shell of a single formamide (FA) molecule. Vibrational frequency through wavelet analysis and correlation function calculations have been performed to understand the spectral signature of water molecules in the first solvation shell and dynamics of solute–solvent hydrogen bonds, respectively. Structural aspects have been analyzed by calculating various pair correlation functions. FA takes part in more than two hydrogen bonds with water via carbonyl oxygen. Due to the presence of carbonyl group, the solvation through amine group hydrogen atoms is asymmetrical; each hydrogen participates in roughly one hydrogen bond. Carbonyl–water hydrogen bonds are stronger than the water–water hydrogen bonds; amine–water hydrogen bonds are much weaker than other two types of hydrogen bonds