分子中电子与正电子湮灭物理机制的理论研究

In the study of positron-molecule interaction field, it is one of the important subject to find the annihilation model, construction of the positron wavefunction and the electron correlation and nuclei vibration effects in the annihilation process. According to the unresolved problem, such as more than hundreds of times bigger than theoretical prediction of the annihilation amplitude of the annihilation process of the positron-molecules, the project intends to take the Roothaan equation as the theoretical support, use the many-body perturbation theory and the Feynman diagram techniques, follow the main line of the resolution of the wavefunction of the positron-molecule systems, focus on the building the model of the annihilation mechanism of the positron-electron pair. It tries to study the influence mechanism of the positron wavefunction and the electron correlation effects on the gamma-ray spectra and the positron annihilation rate, building a set of theory and method to describe exactly the annihilation process based on quantum mechanics, applying to different molecule systems to carry out the accuracy test and the applicability evaluation of the annihilation model. In the present project, the main aim is to investigate and build a set of method to resolve the positron-electron pair wavefunction based on quantum mechanics and build the Fock operators for the electron, positron systems in order to establish the evaluation scheme of the electron-positron pair wavefunction. We will apply to molecules to analyze the electron correlation effects to establish the annihilation models, carry out accuracy test and applicability evaluation. This project will play a significant role in expanding the annihilation methods, and enhance the accuracy of the study of the electron correlation process.

目前正电子与分子相互作用研究主要集中在构建分子中正电子-电子湮灭过程的物理模型、探索正电子-分子体系波函数构造、研究正电子-电子湮灭过程中的电子关联和分子振动效应等方面，并取得了重要进展。但已经发现正电子在几乎所有分子中的湮灭，其湮灭强度比理论值大几十、上百倍，伽马谱宽度亦比理论值大30%以上，这些理论与实验不相符合的物理实质并未阐述清楚。本项目发展基于量子力学方法研究正电子湮灭过程的方法，以Roothaan方程为基础，并结合若干具体正电子-分子体系，利用多体微扰理论和费曼图技术，严格求解正电子-分子体系波函数，在构建正电子-分子体系波函数、电子、正电子Fock算符的基础上，综合运用迭代法等分析技术，构建正电子、电子波函数数值求解方案。通过分析电子关联、分子振动效应对湮灭过程的影响，构建分子中正电子-电子湮灭物理模型。从而阐释分子中正电子湮灭机理，为理解和应用正电子与分子相互作用奠定基础。

目前正电子与分子相互作用研究主要集中在构建分子中正电子-电子湮灭过程的物理.模型、探索正电子-分子体系波函数构造、研究正电子-电子湮灭过程中的电子关联和分子.振动效应等方面，并取得了重要进展。但已经发现正电子在几乎所有分子中的湮灭，其湮.灭强度比理论值大几十、上百倍，伽马谱宽度亦比理论值大30%以上，这些理论与实验不.相符合的物理实质并未阐述清楚。本项目发展基于量子力学方法研究正电子湮灭过程的方.法，以Roothaan方程为基础，并结合若干具体正电子-分子体系，利用多体微扰理论和费.曼图技术，严格求解正电子-分子体系波函数，在构建正电子-分子体系波函数、电子、正.电子Fock算符的基础上，综合运用迭代法等分析技术，构建正电子、电子波函数数值求解.方案。通过分析电子关联、分子振动效应对湮灭过程的影响，构建分子中正电子-电子湮.灭物理模型。从而阐释分子中正电子湮灭机理，为理解和应用正电子与分子相互作用奠定.基础。