MD simulation of an infinitely dilute aqueous solution of formamide, study of thermodynamic, structural, dynamic, and spectroscopic properties

A molecular dynamics simulation of an infinitely dilute aqueous solution of formamide was carried out using an MP2-CP ab initio potential to describe the solute-solvent interaction. Various static and dynamic properties were calculated using this potential obtained by fitting the formamide-water interaction energies to a 12-6-l type function. These energies were calculated with the supermolecular approach by considering the MP2 correlation and the CP superposition. The values presented for the thermodynamic functions (Delta Hs-w = -25.5 kcal-mol(-1) and Delta G(s-w) = - 15.9 kcal-mol(-1)), the structure of the first hydration layer (with 5 to 6 solvent molecules bonded to the solute), the solute's translational (D = 1.50 x 10(-5) cm(2)-s(-1)) and rotational (tau = 6.6 ps) mobility in the surrounding medium, and the positions of the H ... O hydrogen bond spectral bands corresponding to these motions (nu(i) = 92, 246, 379, and 636 cm(-1)), are in agreement with the available results for this and other similar systems. In addition, the results are compared with those obtained by using parameters "transferred" from other systems. We observed that these values depend strongly on the potential used and concluded that it is advisable to avoid the use of such parameters.