Buchowiecki Marcin
Insitute of Physics, University of Szczecin, Wielkopolska 15 St, 70-451 Szczecin, Poland.
J Phys Chem A. 2020 May 21;124(20):4048-4052. doi: 10.1021/acs.jpca.0c01161. Epub 2020 May 8.
The vibrational partition function is calculated using the classical method of integration over the whole phase space. The calculations were done for the ground electronic state of a carbon monoxide molecule. The main focus is on temperature in the range 5000-20 000 K, which is common in hypersonic flows of gases and plasmas. The method presented here, because of the exclusion of the noninteracting part of canonical partition function according to the ideas of T.L. Hill, is applicable at temperatures of tens of thousands of Kelvins, where the standard expression for the vibrational partition function fails. At lower temperatures (here 1000-6000 K), the correct quantum results can be obtained with the help of Wigner-Kirkwood expansion. The influence of vibrations on the rotational partition function by bond-length elongation is examined, and the results are compared with the exact ro-vibrational partition function.
振动配分函数是使用在整个相空间上积分的经典方法来计算的。计算是针对一氧化碳分子的基电子态进行的。主要关注的是5000 - 20000 K范围内的温度，这在气体和等离子体的高超音速流动中很常见。根据T.L.希尔的观点，由于排除了正则配分函数的非相互作用部分，这里提出的方法适用于数万开尔文的温度，而在该温度下振动配分函数的标准表达式失效。在较低温度（这里是1000 - 6000 K）下，借助维格纳 - 柯克伍德展开可以得到正确的量子结果。研究了键长伸长对转动配分函数的振动影响，并将结果与精确的振转配分函数进行了比较。
