Theoretical Study of CH₄−CH₄, CHF₃−CH₄, CH₄−H₂O, and CHF₃−H₂O Dimers

Abstract

We have studied systems with typical hydrogen bonding and others with interaction involving hydrogen. CH(4)-CH(4), CH(4)-H(2)O, CHF(3)-CH(4), and CHF(3)-H(2)O dimers were studied using MPWB1K, PBE1PBE, MP2, and QCISD levels of theory with a large number of basis functions. The Pople 6-31+G(2d), 6-311++G(2d,2p), and 6-311++G(3df,3pd) as well as Dunning augmented aug-cc-pVDZ and aug-cc-pVTZ basis sets were used. The dimer geometries were fully optimized. An optimal basis set was determined for these systems to achieve a suitable compromise between accuracy and computational feasibility. A proper strategy was found for the electronic property calculations of dimers studied: the use of aug-cc-pVDZ as the optimal basis set at MP2 level. Dipole moments, polarizabilities, BSSE effects, and DeltaZPE were also analyzed for these dimers.

Structural Distortions Accompanying Noncovalent Interactions: Methane–Water, the Simplest C–H Hydrogen Bond

“…Interaction energies for this second analysis of the PES are qualitatively displayed in Figure . The three “minima” are denoted A, B, and C. The geometrical arrangement located at point A, which possess the lowest energy, is consistent with the previous structures found by Rovira, Cao, Akin-Ojo, Martins, Patkowski, and Qu for the global minimum on the methane–water PES. Evidence of the difficult nature of studying such a flat PES arises here.…”

“…An important model system in the study of weakly bound noncovalent interactions is the methane–water complex. This system can be seen not only as the simplest hydrophobic interaction but also as the simplest C–H hydrogen bond. , To date, several theoretical studies for this system are available; ,− however, none of them has carefully examined the intramolecular geometrical distortions that occur as the complex is formed.…”

Terahertz vibration-rotation-tunneling spectroscopy of the propane–water dimer: The ortho-state of a 20 cm−1 torsion

“…In the case of water-methane interactions, we have shown [8] that the repulsive wall of the pairwise interaction potential directs the OH bond of water into the threefold hollow of the methyl group, thereby facilitating closest approach of the molecules. Other studies support this conclusion [9,10,11,12]. Extending this picture to higher hydrocarbons is a goal of our ongoing work, and this letter continues that effort.…”

H2O–CH4and H2S–CH4complexes: a direct comparison through molecular beam experiments and ab initio calculations

“…In the present paper, we focused our attention mostly on the water-CH 4 complex, for which several theoretical [19][20][21][22][23] and few experimental 22,24 studies exist in the literature, and on the H 2 S-CH 4 system. 20,22 This investigation represents an extension of previous studies on water-noble gas (Ng), 25 water-H 2 , 26,27 hydrogen sulfide-Ng 28 and hydrogen sulfide-H 2 systems.…”