2014/06/10 by Titantah, John T., Karttunen, Mikko
#Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Soft Condensed Matter (cond-mat.soft)
paper · doi:10.48550/arxiv.1406.2410
We use systematic 8 ns ab initio molecular dynamics (AIMD) to study the structure and dynamics of water in bulk, and close to both hydrophobic and hydrophilic (carbonyl) groups of tetramethylurea (TMU). We observe crossovers in the dynamical behavior around the hydrophobic group at TX = 256 ± 4K and another one at 265 ± 5K related to the relative strength of water-water and water-carbonyl hydrogen bonds (HBs). For bulk water, the temperature of the apparent divergence in relaxation times is located at Tc = 210 ± 10K. To better identify the effects arising from the hydrophilic carbonyl group, systems of water with a methane molecule were used as references. These findings are related to the structural and thermodynamic transitions reported for proteins in solution and may also play a role in the mechanism of cold denaturation of proteins.