ONIOM calculations using CCSD theory have been performed to study the dissociation of hydrogen and water molecules on ZnO surface. Three different cluster models were used to study the influence of ONIOM layer size at the interaction energies and optimized geometries. The geometric results indicate a near tetrahedral geometry for the interaction of zinc and oxygen sites of dissociated water. The interaction energies are larger for the water dissociation. The ONIOM layer size has more influence on the interaction energies when compared with the geometric parameters and mainly for water dissociation. © 2012 Wiley Periodicals, Inc.

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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.

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In this work, we performed a thorough investigation of potential energy curves, rovibrational spectra, and spectroscopic constants for dimers whose interactions are mediated by hydrogen bonds and other hydrogen interactions. Particularly, we deal with CH4⋯CH4, CH4⋯H2O, CH4⋯CHF3, and H2O⋯CHF 3 dimers by employing accurate electronic energy calculations with two different basis sets at the MP2 level of theory. Following this, the discrete variable representation method was applied to solve the nuclear Schrödinger equation, thus obtaining spectroscopic constants and rovibrational spectra. The harmonic constant, ω e , presents a direct relation to the strength of dimer interactions. As a general rule, it was found that a decrease of interatomic distances is followed by the increase of D e for all dimers. This behavior suggests that the interaction of CH4⋯CH4 is the weakest among all dimers, followed by CH4⋯CHF3, CH4⋯H2O and the strongest interaction given by the H2O⋯CHF 3 dimer.

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Atualmente existe uma grande preocupação na busca de fontes alternativas de produção que degradem o meio ambiente o mínimo possível. Nesse sentido, há uma disposição muito grande em reduzir a dependência da sociedade atual dos derivados de petróleo, substituindo estes por materiais renováveis e sustentáveis. A partir dessa visão ambiental e sustentável, este trabalho avalia o uso de óleo vegetal e alguns de seus derivados como alternativa aos óleos lubrificantes de matriz mineral. O óleo vegetal estudado nesse trabalho foi o óleo de Canola que é produzido em abundância no Brasil. As propriedades físico-químicas investigadas para avaliar a viabilidade deste óleo e seus derivados como base lubrificante foram índice de acidez, viscosidade cinemática e estabilidade oxidativa. O diol e o diéster produzidos a partir do óleo de Canola melhoraram a viscosidade e a estabilidade oxidativa em comparação com o óleo natural, mas mostrou pequeno aumento na acidez. Essas características indicam que o óleo de Canola "in natura" e os derivados que foram produzidos a partir dele podem se tornar viáveis alternativa aos óleos lubrificantes de matriz mineral.

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