Åstrand Per-Olof
Department of Chemistry, NTNU - Norwegian University of Science and Technology, NO-7481 Trondheim, Norway.
J Phys Chem Lett. 2024 Jun 13;15(23):6146-6150. doi: 10.1021/acs.jpclett.4c01297. Epub 2024 Jun 4.
A model for the molecular ionization energy in an applied electric field is presented on the basis of a perturbation expansion in the electric field. The leading term arises from the Frenkel approach, which is the same for all molecules normally used in the Poole-Frenkel model for conductivity in an electric field. For a set of test molecules, the quality of the results is comparable to that of previous results using constrained density functional theory. We conclude that the Frenkel term is dominant and sufficient at relatively low fields and that the dipole and polarizability terms, the leading terms dependent on the properties of the individual molecule, make a significant contribution only at high fields and for relatively large molecules. Because the presented model is analytical, quantum chemical calculations are avoided for a variety of electric field strengths and molecular orientations, and the model can therefore be applied directly in coarse-grained models for electronic processes in dielectric condensed phases.
基于电场中的微扰展开，提出了一种应用电场中分子电离能的模型。主导项源自弗伦克尔方法，对于电场中电导率的普尔-弗伦克尔模型中通常使用的所有分子而言，该方法都是相同的。对于一组测试分子，结果的质量与先前使用约束密度泛函理论得到的结果相当。我们得出结论，在相对低的场强下，弗伦克尔项占主导且足够，而偶极矩和极化率项（依赖于单个分子性质的主导项）仅在高场强且对于相对较大的分子时才会做出显著贡献。由于所提出的模型是解析的，因此对于各种电场强度和分子取向都无需进行量子化学计算，该模型因此可直接应用于介电凝聚相电子过程的粗粒化模型中。
