Visualizing Internal Stabilization in Weakly Bound Systems Using Atomic Energies: Hydrogen Bonding in Small Water Clusters

Abstract

Atomic energies are used to visualize the local stabilizing and destabilizing energy changes in water clusters. Small clusters, (H(2)O)(n), from n = 2-5, at MP2/aug-cc-pVTZ geometries are evaluated using energies defined by the quantum theory of atoms in molecules (QTAIM). The atomic energies reproduce MP2 total energies to within 0.005 kcal mol(-1). Oxygen atoms are stabilized for all systems and hydrogen atoms are destabilized. The increased stability of the water clusters due to hydrogen bond cooperativity is demonstrated at an atomic level. Variations in atomic energies within the clusters are correlated to the geometry of the waters and reveal variations in the hydrogen bond strengths. The method of visualization of the energy changes applied here is especially suited for application to large biomolecules.

A combined experimental and theoretical approach to the study of hydrogen bond interaction in the binary mixture of N-methylimidazole with water

“…Selected hydrogen bond TABLE 2 Coefficients (A i /cm 3 Ámol À1 ) of the fitting equation (2) and standard deviations (SD/cm 3 Á mol À1 ) of MeIm (1) + water (2) mixture at T = (288.15 to 323.15) K. lengths all fall in the generally accepted range of a hydrogen bond. From table 3, the corrected interaction energy calculated for the water dimer (V) is found to be À21.20 kJ Á mol À1 , which is comparable with the previously reported [46] values of À20.67 kJ Á mol À1 . The uncorrected and corrected interaction energies absolute for all dimers increase in the order of I > V > IV > III > II, which shows that the (MeIm + H 2 O) dimer (I) is most favoured in the binary mixture.…”

The nature of resonance-assisted hydrogen bonds: a quantum chemical topology perspective

“…As established in previous studies on H-bonds, 13,43,44,59,60 the formation of an RAHB leads to a noticeable redistribution of electron density across the molecule. These changes are in agreement with conventional arrow pushing in conjugated unsaturated systems.…”

Making and breaking of small water clusters: A combined quantum chemical and molecular dynamics approach

“…The HBSBIC value for the trimer is calculated as 0.123, whereas the dimer exhibits a significantly higher value of 0.154. In the higher order n ‐mers, the hydrogen bond strength increases with increasing n for the case of full geometry optimization in the gas phase as well as on implicit solvation in agreement with the existing literature . The higher order n ‐mers exhibit only a slight or no increase in HBSBIC values obtained from the single‐point calculations.…”

“…While the Gaussian runs for full geometry optimizations implementing the PCM solvent model were performed at both MP2/6–311++g** and MP2/aug‐cc‐pVTZ levels of theory, the gas phase calculations (at MP2/aug‐cc‐pVTZ level of theory) were directly taken from a paper co‐authored by the author of the present paper. Note that MP2 is a well established method to describe H‐bonded systems …”