Parallel Monte Carlo Calculations of Condensed Quantum Systems

这是一个正在进行的量子模拟研究的更新补助金 多体系统 改进的技术和计算能力将 在一些更困难和复杂的问题上取得进展 问题 将对结构进行详细研究， 氦膜的相、结构和激发能 量子化涡旋，氦-4的流体和固体相 非常接近融化-凝固转变。 一个新的费米子 算法将被应用于研究氦-3的流体相 以及之前对动量分布和凝聚态的计算 氦-4的分数将使用新的采样得到改善 技术和改进的波函数。 一项新的研究将 在地面和激发态的氦-3 液氦中杂质。 将尝试构建一个 量子力学软势问题的一般方法 基于硬核建模和适当的扰动方法， 两体势的剩余部分。 形式主义将是 发展了模拟量子的路径积分方法， 有限温度下的系统。 %%% 正在进行的研究项目将集中在计算 氦在液体中的重要问题的模拟 和固态。 这是一个困难的、非常根本的问题 因为量子力学效应对这些系统来说并不小。 为了处理这些计算密集型问题，新的 计算机技术将得到发展。

This is a renewal grant for ongoing simulation studies of quantum many-body systems. Improved techniques and computing power will enable progress to be made on several more difficult and complex problems. Detailed studies will be made on the structure and phases of helium films, the structure and excitation energy of a quantized vortex, and the fluid and solid phases of helium-four very close to the melting-freezing transition. A new Fermion algorithm will be applied to study the fluid phase of helium-three and prior calculations on the momentum distribution and condensate fraction of helium-four will be improved using new sampling techniques and improved wave functions. A new study will be initiated on the ground and excited states of a helium-three impurity in liquid helium. An attempt will be made to construct a general approach to quantum mechanical soft potential problems based on hard-core modeling and a suitable perturbation approach to the remainder of the two-body potential. The formalism will be developed for the path integral method of simulating quantum systems at finite temperatures. %%% The ongoing research project will focus on the computational simulation of important problems concerning helium in its liquid and solid states. This is a difficult and very fundamental problem since quantum mechanical effects are not small for these systems. In order to deal with these computationally intensive problems, new computer techniques will be developed.