Department of Physics, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere, Finland.
J Chem Phys. 2011 Sep 14;135(10):104310. doi: 10.1063/1.3633516.
For the first time, the equilibrium composition of chemical dissociation-recombination reaction is simulated from first-principles, only. Furthermore, beyond the conventional ab initio Born-Oppenheimer quantum chemistry the effects from the thermal and quantum equilibrium dynamics of nuclei are consistently included, as well as, the nonadiabatic coupling between the electrons and the nuclei. This has been accomplished by the path integral Monte Carlo simulations for full NVT quantum statistics of the H(3)(+) ion. The molecular total energy, partition function, free energy, entropy, and heat capacity are evaluated in a large temperature range: from below room temperature to temperatures relevant for planetary atmospheric physics. Temperature and density dependent reaction balance of the molecular ion and its fragments above 4000 K is presented, and also the density dependence of thermal ionization above 10,000 K is demonstrated.
首次仅从第一性原理出发模拟了化学离解-复合反应的平衡组成。此外，除了传统的从头算 Born-Oppenheimer 量子化学之外，还一致地包含了核的热和量子平衡动力学以及电子与核之间的非绝热耦合。这是通过路径积分蒙特卡罗模拟来实现的，用于 H(3)(+)离子的全 NVT 量子统计。在很宽的温度范围内评估了分子总能量、配分函数、自由能、熵和热容：从低于室温到与行星大气物理相关的温度。给出了 4000 K 以上分子离子及其碎片的温度和密度相关的反应平衡，也证明了 10000 K 以上的热电离的密度依赖性。
