基于密度泛函理论对等离子体中H/CO2相互作用的第一性原理研究

深入理解辐照条件下氢同位素与CO₂反应的微观机制，可为聚变堆氘氚燃料循环工艺的优化设计提供数据支撑。基于此，采用第一性原理计算研究了等离子体放电条件下H₂和CO₂的微观反应机制，研究了不同温度和氢同位素效应对反应过程的影响。通过内禀反应坐标（IRC）算法结合反应过渡态获得4条初始反应路径，并对比研究了生成产物CH₄及CH₃OH的2条路径在热力学上的容易程度，以及不同氢同位素对各个反应的影响。研究发现，氚的自发衰变或等离子体中的高能电子都会诱导氢同位素与CO₂发生反应，形成CO、H₂O、CH₄及CH₃OH等产物；在高能电子诱导CO₂的离解后，由4条初始反应路径组成的复杂反应可以自持发生，且该复杂反应中存在2种倾向；升高反应温度对CO₂转化为有机物（CH₄和CH₃OH）具有一定的促进作用。

First-Principles Calculation of H/CO2 Interaction in Plasma: A Density Functional Theory-Based Study

An in-depth understanding of the microscopic mechanism of the reaction of hydrogen isotopes with CO₂ under irradiation conditions can provide data support for the optimal design of the deuterium-tritium fuel cycle process for fusion reactors. Based on this, the microscopic reaction mechanism of H₂ and CO₂ under the condition of plasma discharge was studied by first-principles calculation, and the influences of different temperatures and hydrogen isotope effect on the reaction process were studied. The principal calculation was carried out by the Gaussian 09 software package. The enthalpies and activation energies of these reactions were measured at the level of M06-2X/6-311++G (3d2f, 3p2d). Four initial reaction paths are obtained by using the intrinsic reaction coordinate (IRC) algorithm and finding the transition state of the combined reaction. The thermodynamic easiness of the two pathways to produce CH₄ and CH₃OH and the influence of different hydrogen isotopes on each reaction were compared and studied. It is found that the spontaneous decay of tritium or the high-energy electrons in the plasma will induce hydrogen isotopes to react with CO₂ to form products such as CO, H₂O, CH₄, and CH₃OH; after the high-energy electrons induce the dissociation of CO₂, there are four initial reaction paths. Complex reactions can occur on their own, and there are two tendencies to this complex reaction. Raising the reaction temperature has a certain promoting effect on the conversion of CO₂ into organic matter (CH₄ and CH₃OH).