Molecules under external electric field: On the changes in the electronic structure and validity limits of the theoretical predictions

• Published in: Journal of computational chemistry Vol. 39; no. 20; pp. 1561 - 1567
• Main Authors: Pansini, F. N. N., de Souza, F. A. L., Campos, C. T.
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 30.07.2018
• Subjects: ab initio calculation; Diatomic molecules; electric field; Electric fields; electric response properties; Electronic structure; Energy gap; Molecular chains; Molecular orbitals; spin state transition; Spin transition; Taylor series; ab initio calculation; electric field; spin state transition; electric response properties
• ISSN: 0192-8651; 1096-987X
• DOI: 10.1002/jcc.25229

A detailed analysis of the electronic structure of the ground and first excited spin state of three diatomic molecules ( N2, BH and CO) under static applied electric field is performed at CCSD(T), DFT, MRCI and MRCI(Q) levels of theory. Our findings have revealed that by boosting the applied field one induces changes in the occupation numbers of molecular orbitals, giving rise to changes in the equilibrium geometry and in the HOMO–LUMO energy gap. Specifically, singlet to triplet spin transition can be induced by increasing the applied electric field beyond a critical value. Accordingly, affecting the accuracy of the widely used expression of energy expanded in Taylor series with respect to the applied electric field. © 2018 Wiley Periodicals, Inc. A detailed electronic structure analysis of ground and first excited spin state of three diatomic molecules under static applied electric field via DFT and ab initio methods is presented. Findings reveal that by boosting the applied field one induces changes in the molecular orbital occupation numbers, equilibrium geometry, and in the HOMO‐LUMO energy gap. In special, electrically driven spin state, transitions can be promoted by increasing the applied field beyond a critical value.