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采用量子化学方法中的密度泛函理论B3LYP方法,在B3LYP/6-311++G(d,p)基组水平上,对直链酸(甲酸至庚酸)与单分子水形成的体系进行结构优化和频率计算,从分子水平上研究了体系的相关的结构参数、电荷分布以及结合能,运用AIM理论分析了体系的电了密度拓扑。结果表明:直链酸与水形成两个氢键,其中羧基中氢原子作为质子供体的氢键1的键能强于水的氢作为质子供体的氢键2的键能。氢键1对体系的结合能影响起主导作用。稳定构型为六元环构型。直链酸与水结合能不随碳链增长呈明显变化,在(38.7-39.7)kJ/mol之间。
The B3LYP method of density functional theory (QFT) in quantum chemistry was used to study the formation of a linear acid (formic acid to heptanoic acid) and monomolecular water at B3LYP / 6-311 ++ G (d, p) Structure optimization and frequency calculation. The related structural parameters, charge distribution and binding energy of the system were studied at the molecular level. The electric density topologies of the system were analyzed by AIM theory. The results show that the linear acid forms two hydrogen bonds with water, in which the hydrogen bond in the carboxyl group acts as proton donor and the bond of hydrogen bond 1 is stronger than that of water as the bond energy of proton donor hydrogen bond. Hydrogen bond 1 plays a leading role in the binding of the system. The stable configuration is a six-membered ring configuration. The linear acid and water binding energy does not change significantly with the carbon chain growth, at (38.7-39.7) kJ / mol between.