Authors : Venkata Siva Surya Kolla

Volume/Issue : Volume 11 - 2026, Issue 7 - July

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Google Scholar : https://tinyurl.com/3sj22r8w

Scribd : https://tinyurl.com/mr2bsbrz

DOI : https://doi.org/10.38124/ijisrt/26jul1745

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Abstract : In this article, acetonitrile, paranitroaniline, and trans-butadiene were chosen as simple molecular models for popular molecular systems, and the behaviour of the HOMO and LUMO orbitals of the molecules was studied under external electric fields using the B3LYP functional and the 6-31G basis set within density functional theory (DFT). Acetonitrile demonstrated first-order electronic perturbation; Paranitroaniline showed relatively higher orbital sensitivity; and finally, trans-butadiene demonstrated non-linear behaviour. Electronic perturbation theory is used to explain the behaviour of the molecules and highlight characteristics that might be favourable or unfavourable for applications in molecular electronics.

Keywords : Single-Molecule Transistors, Density Functional Theory, HOMO-LUMO Orbital Tuning, Electronic Perturbation Theory, Hückel Molecular Orbital Theory, Effect of Electron-Donating or Withdrawing Substituents on Orbital Behaviour, Electric Field Effects on Conjugated Polyenes, Effects of A Permanent Dipole Moment.

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