Self-optimizing Diffusion Quantum Monte Carlo Calculation: the Potential Energy Curve of C_2

In this paper we propose a novel diffusion quantum Monte Carlo algo-rithm, it is a self-optimizing and self-improving procedure. The method has been em-ployed to calculate the potential energy curve of C2. The total energies for the X 1Σg+state of C2 were calculated at seven values of the bond length: 0. 106, 0. 111, 0. 124,0. 132, 0. 143, 0. 159 and 0. 185 nm; and a smooth potential energy curve was ob-tained, because when the self-optimizing technique is used, the statistical error decreas-es tremendously. The calculation results on the potential energy curve of C2 show thatthe self-optimizing diffusion quantum Monte Carlo method proposed in the present pa-per is successful.

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本文研究了一类非公度系统中电子运动的能谱及其与电子动力学性质的联系 ,分析了体系的本征能量E与参数λ的关系 ,计算了自关联函数C(t)和均方位移σ(t) ,分析其长期行为 ,发现当体系各态均为扩展态时 ,σ(t)～t1,C(t)～t- 1,当体系中仅存在局域态时 ,σ(t)～t0 ,C(t)～t0 ;当体系在复杂相区时 ,体系的长期行为 ,即t→∞时 ,σ(t)～t1。