Ab initio study of the positronation of the CaO and SrO molecules including calculation of annihilation rates
Ab initio study of the positronation of the CaO and SrO molecules including calculation of annihilation rates
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CaO 和 SrO 分子正电子化的从头算研究，包括湮灭率的计算
DOI：
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发表时间：
2012
影响因子：
3
通讯作者：
H. Liebermann
中科院分区：
文献类型：
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作者：
R. Buenker;H. Liebermann
采用从头算多参考单激发和双激发组态相互作用计算了CaO和SrO分子及其正电子复合物e+CaO和e+SrO的基态和激发态的势能曲线。后一个系统的最低态的绝热解离极限由正金属离子基态（M+）和OPs复合物（e+O−）组成，尽管最低能量极限被认为是e+M + O。中性双光子晶体的光谱常数计算值与实验值吻合较好。两个系统的闭合壳层X 1 π +基态的正电子亲合势都在0.16-0.19 eV范围内，不到碱土金属一氧化物系列中较轻成员BeO和MgO相应值的一半。第一次计算了所有四个正电子系统的湮没率（AR）。随着键距的变化一般是类似的碱金属一氧化物系列的正电子复合物，逐渐下降，从OP AR值在各自的解离极限。e+SrO系统表现出一些特殊的行为，然而，其AR值达到最小值在一个相对较大的键距，然后上升到两倍以上的OPs值接近其平衡距离。© 2012 Wiley Periodicals，Inc.
Ab initio multireference single‐ and double‐excitation configuration interaction calculations have been performed to compute potential curves for ground and excited states of the CaO and SrO molecules and their positronic complexes, e+CaO, and e+SrO. The adiabatic dissociation limit for the 2Σ+ lowest states of the latter systems consists of the positive metal ion ground state (M+) and the OPs complex (e+O−), although the lowest energy limit is thought to be e+M + O. Good agreement is found between the calculated and experimental spectroscopic constants for the neutral diatomics wherever available. The positron affinity of the closed‐shell X 1Σ+ ground states of both systems is found to lie in the 0.16–0.19 eV range, less than half the corresponding values for the lighter members of the alkaline earth monoxide series, BeO and MgO. Annihilation rates (ARs) have been calculated for all four positronated systems for the first time. The variation with bond distance is generally similar to what has been found earlier for the alkali monoxide series of positronic complexes, falling off gradually from the OPs AR value at their respective dissociation limits. The e+SrO system shows some exceptional behavior, however, with its AR value reaching a minimum at a relatively large bond distance and then rising to more than twice the OPs value close to its equilibrium distance. © 2012 Wiley Periodicals, Inc.