Klauda Jeffery B, Pastor Richard W, Brooks Bernard R
J Phys Chem B. 2005 Aug 25;109(33):15684-6. doi: 10.1021/jp0527608.
High-level ab initio quantum mechanical calculations are used to study various gauche conformational energies of n-pentane to n-decane. The destabilizing "pentane effect" (adjacent gauche states of opposite sign) for alkanes is confirmed, but the energies were found to depend slightly on chain length. In contrast, introducing an adjacent gauche of the same sign requires only 0.22-0.37 kcal/mol, approximately half of the single gauche state energy. This adjacent gauche stabilization should be taken into account when formulating or analyzing rotational isomeric models, carrying out conformational analysis, and developing force fields for alkanes, lipids, and related polymers.
采用高水平的从头算量子力学计算方法研究正戊烷至正癸烷的各种gauche构象能量。确认了烷烃中存在不稳定的“戊烷效应”（符号相反的相邻gauche态），但发现能量对链长有轻微依赖性。相比之下，引入相同符号的相邻gauche态仅需0.22 - 0.37千卡/摩尔，约为单个gauche态能量的一半。在构建或分析旋转异构体模型、进行构象分析以及开发烷烃、脂质和相关聚合物的力场时，应考虑这种相邻gauche态的稳定作用。
