In the present work, electro-optical and electronic properties of 4-n-pentyl-\(4^{\prime }\)-cyanobiphenyl (5CB) and \(4^{\prime }\)-cyano-4-n-pentyl-p-terphenyl (5CT) liquid crystal molecules have been investigated. The 5CB compound transforms from crystal to nematic phase at 24\(^\circ \)C and nematic to isotropic phase at 35.3\(^\circ \)C while 5CT compound transforms from crystal to nematic phase at 130\(^\circ \)C and nematic to isotropic phase at 239\(^\circ \)C. Molecular geometry of 5CB and 5CT have been optimised by DFT method with 6-31G(d,p) basis set. Binding energies acting between dimers have been calculated. Mulliken and natural population analyses have been done. The HOMO–LUMO surfaces, molecular and thermodynamic properties have been examined. The excitation energy and oscillator strength have been calculated by TD-DFT/B3LYP/6-31G(d,p) method. All the investigated parameters of 5CT have been compared with that of 5CB molecule. Results have been used to elucidate the electro-optical and electronic properties of 5CB and 5CT molecules.

在目前的工作中，4-n-戊基- （4 ^ {\ prime} \）-氰基联苯（5CB）和\（4 ^ {\ prime} \）-氰基-4-n的电光和电子性质-戊基-对-叔苯基（5CT）液晶分子已得到研究。从晶体到向列相的5CB化合物变换为24 \（^ \ CIRC \）下和在35.3向列到各向同性相\（^ \ CIRC \） C，而从晶体5CT化合物变换以向列相在130 \（^ \ CIRC \）在239 \（^ \ circ \）的C和向列至各向同性的相C. 5CB和5CT的分子几何结构已通过DFT方法以6-31G（d，p）为基础进行了优化。已经计算了在二聚体之间起作用的结合能。Mulliken和自然人口分析已经完成。已经检查了HOMO-LUMO表面，分子和热力学性质。激励能量和振荡器强度已通过TD-DFT / B3LYP / 6-31G（d，p）方法计算出。已将5CT的所有研究参数与5CB分子的参数进行了比较。结果已用于阐明5CB和5CT分子的光电特性。