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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Modeling positrons in molecular electronic structure calculations with the nuclear-electronic orbital method
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Modeling positrons in molecular electronic structure calculations with the nuclear-electronic orbital method

机译：用核电子轨道方法在分子电子结构计算中对正电子建模

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摘要

The nuclear-electronic orbital (NEO) method was modified and extended to positron systems for studying mixed positronic-electronic wavefunctions, replacing the mass of the proton with the mass of the positron. Within the modified NEO framework, the NEO-HF (Hartree-Fock) method provides the energy corresponding to the single-configuration mixed positronic-electronic wavefunction, minimized with respect to the molecular orbitals expressed as linear combinations of Gaussian basis functions. The electron-electron and electron-positron correlation can be treated in the NEO framework with second-order perturbation theory (NEO-MP2) or multiconfigurational methods such as the full configuration interaction (NEO-FCI) and complete active space self-consistent-field (NEO-CASSCF) methods. In addition to implementing these methods for positronic systems, strategies for calculating electron-positron annihilation rates using NEO-HF, NEO-MP2, and NEO-FCI wavefunctions were also developed. To apply the NEO method to the positronium hydride (PsH) system, positronic and electronic basis sets were optimized at the NEO-FCl level and used to compute NEO-MP2 and, NEO-FCI energies and annihilation rates. The effects of basis set size on NEO-MP2 and NEO-FCI correlation energies and annihilation rates were compared. Even-tempered electronic and positronic basis sets were also optimized for the e(+)LiH molecule at the NEO-MP2 level and used to compute the equilibrium bond length and vibrational energy.
机译：修改了核电子轨道（NEO）方法，并将其扩展到正电子系统以研究混合正电子波函数，用正电子质量代替了质子质量。在改进的NEO框架内，NEO-HF（Hartree-Fock）方法提供的能量对应于单配置混合正电子波函数，相对于表示为高斯基函数线性组合的分子轨道而言，该能量最小。可以使用二阶微扰理论（NEO-MP2）或多组态方法（例如全组态相互作用（NEO-FCI）和完整的活性空间自洽场）在NEO框架中处理电子-电子和电子-正电子相关性（NEO-CASSCF）方法。除了将这些方法用于正电子系统之外，还开发了使用NEO-HF，NEO-MP2和NEO-FCI波函数计算电子-正电子an灭率的策略。为了将NEO方法应用于氢化正电子（PsH）系统，在NEO-FC1级别优化了正电子和电子基础集，并用于计算NEO-MP2以及NEO-FCI的能量和an灭率。比较了基集大小对NEO-MP2和NEO-FCI相关能量和an灭率的影响。还对在NEO-MP2水平上的e（+）Li​​H分子优化了均匀回火的电子和正电子基础集，并用于计算平衡键长和振动能。

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