Physics, Sambalpur University Institute of Information Technology (SUIIT), Sambalpur, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2014 Jan 3;117:315-22. doi: 10.1016/j.saa.2013.07.105. Epub 2013 Aug 8.
Molecular structure in optimum geometry and vibrational frequencies of pentafulvalene [bicyclopentyliden-2,4,2',4'-tetraene], tetrathiafulvalene [2,2'-bis(1,3-dithiolylidene)] and its cation are calculated. All the calculations are carried out by employing density functional theory incorporated with a suitable basis set. Normal coordinate analysis is also employed to scale the DFT calculated frequencies and to calculate potential energy distributions. The molecular structures and vibrational frequencies are compared for both the pentafulvalene and tetrathiafulvalene molecules. The effect upon geometry and vibrational frequencies of TTF due to charge transfer has also been studied. The vibrational partition function and hence, the thermodynamical properties, such as Helmholtz free energy, entropy, specific heat at constant volume and enthalpy are also calculated and compared for the title molecules. The reason of conductivity of tetrathiafulvalene has been tried to explain on the basis of molecular geometry and normal modes. Study of vibrational partition function exhibits that below 109 K, PFV starts to condense.
计算了五并苯[双环戊二烯-2,4,2',4'-四烯]、四硫富瓦烯[2,2'-双(1,3-二硫代亚烯基)]及其阳离子的最佳几何形状和振动频率的分子结构。所有的计算都是通过密度泛函理论与合适的基组相结合来进行的。还进行了正则坐标分析，以缩放 DFT 计算的频率并计算势能分布。比较了五并苯和四硫富瓦烯分子的分子结构和振动频率。还研究了电荷转移对 TTF 几何形状和振动频率的影响。还计算并比较了标题分子的振动配分函数，从而计算了热力学性质，如亥姆霍兹自由能、熵、定容比热容和焓。根据分子几何形状和正则模式，尝试解释了四硫富瓦烯的导电性的原因。振动配分函数的研究表明，在 109 K 以下，PFV 开始凝聚。
