Barbatti Mario
Aix Marseille University, CNRS, ICR, Marseille, France and Institut Universitaire de France, 75231 Paris, France.
J Chem Phys. 2022 May 28;156(20):204304. doi: 10.1063/5.0090205.
The microcanonical temperature of an isolated molecule is derived in terms of Boltzmann and Gibbs volume entropies within the quantum harmonic vibrational and equivalent degenerated model approximations. The effects of the entropy functional choice and various approximations are examined. The difference between Boltzmann and Gibbs volume temperatures is negligible for molecules bigger than ten atoms. However, it is significant for smaller systems, opening a way to probe them experimentally. A simple, analytical expression of the temperature as a function of the vibrational energy is provided, allowing predictions with a ±3% margin of error compared to the exact harmonic estimate. The microcanonical temperature is discussed and exemplified with polycyclic aromatic hydrocarbon molecules and other molecules of astrophysical interest.
在量子简谐振子和等效简并模型近似下，根据玻尔兹曼熵和吉布斯体积熵推导出孤立分子的微正则温度。研究了熵函数选择和各种近似的影响。对于大于十个原子的分子，玻尔兹曼体积温度和吉布斯体积温度之间的差异可以忽略不计。然而，对于较小的系统，这种差异是显著的，这为通过实验探测它们开辟了一条途径。提供了一个简单的温度作为振动能量函数的解析表达式，与精确的简谐估计相比，预测误差幅度为±3%。对微正则温度进行了讨论，并以多环芳烃分子和其他具有天体物理意义的分子为例进行了说明。
