C_PDMATHAAAA烷烃异构体（n = 2 - 8）的基准热化学和DFT及复合从头算方法对分散驱动异构体平衡的性能
Benchmark thermochemistry of the C_nH_{2n+2} alkane isomers (n=2--8) and performance of DFT and composite ab initio methods for dispersion-driven isomeric equilibria
摘要：
本文用W_4、W_3.2lite和W_1h理论重新研究了八碳以下直链和支链烷烃的热化学。通过等键和次同键反应获得了"准W4"原子化能。我们在0 K时的最佳原子化能量（kcal/mol）为：1220.04正丁烷，1497.01正戊烷，1774.15正己烷，2051.17正庚烷，2328.30正辛烷，1221.73异丁烷，1498.27异戊烷，1501.01新戊烷，1775.22异己烷，1774.61 3-甲基戊烷，1775.67二异丙基、1777.27新己烷、2052.43异庚烷、2054.41新庚烷、2330.67异辛烷和2330.81六甲基乙烷。我们对$ΔH^\circ_{f,298K}$的最佳估计为：-30.00正丁烷、-34.84正戊烷、-39.84正己烷、-44.74正庚烷、-49.71正辛烷、-32.01异丁烷、-36.49异戊烷、-39.69新戊烷、-41.42异己烷、-40.72 3-甲基戊烷、-42.08二异丙基、-43.77新己烷，-46.43异庚烷、-48.84新庚烷、-53.29异辛烷和-53.68六甲基乙烷。这些是在极好的协议（通常优于1 kJ/mol），在298 K的实验生成热从CCCBDB和/或NIST化学网络图书数据库。然而，在0 K的理论和实验（1.1千卡/摩尔）之间的一个很大的差异观察到只有新戊烷。这种偏差主要是由于在计算0 K CCCBDB值时使用了错误的新戊烷热含量函数。这些系统的热化学，特别是较大的烷烃，是一个非常困难的测试密度泛函方法。色散的后验修正是必不可少的。特别是对于原子化能，B2GP-PLYP和B2K-PLYP双杂化，以及PW6B95杂化-meta GGA明显优于其他DFT泛函。
英文摘要：
The thermochemistry of linear and branched alkanes with up to eight carbons has been reexamined by means of W4, W3.2lite and W1h theories. `Quasi-W4' atomization energies have been obtained via isodesmic and hypohomodesmotic reactions. Our best atomization energies at 0 K (in kcal/mol) are: 1220.04 n-butane, 1497.01 n-pentane, 1774.15 n-hexane, 2051.17 n-heptane, 2328.30 n-octane, 1221.73 isobutane, 1498.27 isopentane, 1501.01 neopentane, 1775.22 isohexane, 1774.61 3-methylpentane, 1775.67 diisopropyl, 1777.27 neohexane, 2052.43 isoheptane, 2054.41 neoheptane, 2330.67 isooctane, and 2330.81 hexamethylethane. Our best estimates for $ΔH^\circ_{f,298K}$ are: -30.00 n-butane, -34.84 n-pentane, -39.84 n-hexane, -44.74 n-heptane, -49.71 n-octane, -32.01 isobutane, -36.49 isopentane, -39.69 neopentane, -41.42 isohexane, -40.72 3-methylpentane, -42.08 diisopropyl, -43.77 neohexane, -46.43 isoheptane, -48.84 neoheptane, -53.29 isooctane, and -53.68 hexamethylethane. These are in excellent agreement (typically better than 1 kJ/mol) with the experimental heats of formation at 298 K obtained from the CCCBDB and/or NIST Chemistry WebBook databases. However, at 0 K a large discrepancy between theory and experiment (1.1 kcal/mol) is observed for only neopentane. This deviation is mainly due to the erroneous heat content function for neopentane used in calculating the 0 K CCCBDB value. The thermochemistry of these systems, especially of the larger alkanes, is an extremely difficult test for density functional methods. A posteriori corrections for dispersion are essential. Particularly for the atomization energies, the B2GP-PLYP and B2K-PLYP double-hybrids, and the PW6B95 hybrid-meta GGA clearly outperform other DFT functionals.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
