Understanding the impulse discharge behaviour of natural ester (NE) is crucial for its safe application in high-voltage transformers. The ionisation potential (IP) of triglycerides plays a significant role in the process of molecular ionisation during impulse discharge for NE. The correlation coefficients between molecular size, frontier orbital, electrostatic potential, polarity, and IP were analysed. And the quantitative microstructure-IP model for triglycerides were built, which revealed that IP is strongly related to the highest occupied molecular orbital (HOMO) energy E_HM, as well as the average value of positive electrostatic potential V_p(+), the average value of negative electrostatic potential V_p(−), and the surface area of negative electrostatic potential S(−). The HOMO and negative electrostatic potentials of saturated triglycerides are predominantly linked to the carbonyl O atoms. Conversely, in unsaturated triglycerides, the influence of C=C double bonds on HOMO and negative electrostatic potentials is more pronounced. Therefore, the IP of unsaturated NE with C=C bonds is lower than that of saturated NE, rendering it more susceptible to ionisation under a strong electric field which is unfavourable for impulse breakdown voltage. The structure-property correlation analysis is valuable for understanding ionisation mechanism during the impulse discharge breakdown of NE at the microscopic level.

中文翻译：

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通过 DFT 计算进行微结构-电离势关系分析，了解脉冲放电过程中天然酯的分子电离差异

了解天然酯 (NE) 的脉冲放电行为对于其在高压变压器中的安全应用至关重要。甘油三酯的电离势 (IP) 在 NE 脉冲放电期间的分子电离过程中起着重要作用。分析了分子大小、前线轨道、静电势、极性和IP之间的相关系数。并建立了甘油三酯的定量微观结构-IP模型，揭示了IP与最高占据分子轨道（HOMO）能量E _HM以及正静电势平均值V _p (+)、平均负静电势V _{p (-)的值和负静电势}S (-)的表面积。饱和甘油三酯的 HOMO 和负静电势主要与羰基 O 原子相连。相反，在不饱和甘油三酯中，C=C双键对HOMO和负静电势的影响更为明显。因此，具有C=C键的不饱和NE的IP低于饱和NE，使其在强电场下更容易电离，不利于脉冲击穿电压。结构-性质相关分析对于在微观水平上理解NE脉冲放电击穿过程中的电离机制具有重要意义。