Chakraborty Arindam, Truhlar Donald G
Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455-0431, USA.
J Chem Phys. 2006 May 14;124(18):184310. doi: 10.1063/1.2193521.
The vibrational partition function of ethane is calculated in the temperature range of 200-600 K using well-converged energy levels that were calculated by vibrational configuration interaction, and the results are compared to the harmonic oscillator partition function. This provides the first test of the harmonic oscillator approximation for a molecule with more than five atoms. The absolute free energies computed by the harmonic oscillator approximation are in error by 0.59-0.62 kcal/mol over the 200-600 K temperature range.
使用通过振动组态相互作用计算得到的收敛良好的能级，计算了乙烷在200 - 600 K温度范围内的振动配分函数，并将结果与谐振子配分函数进行了比较。这为具有五个以上原子的分子的谐振子近似提供了首次检验。在200 - 600 K温度范围内，由谐振子近似计算得到的绝对自由能误差为0.59 - 0.62 kcal/mol。
