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首页> 外文期刊>The Journal of Chemical Physics >Path integral molecular dynamics method based on a pair density matrix approximation: An algorithm for distinguishable and identical particle systems
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Path integral molecular dynamics method based on a pair density matrix approximation: An algorithm for distinguishable and identical particle systems

机译:基于对密度矩阵近似的路径积分分子动力学方法:一种可区分且相同的粒子系统的算法

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In this paper, the path integral molecular dynamics (PIMD) method has been extended to employ an efficient approximation of the path action referred to as the pair density matrix approximation. Configurations of the isomorphic classical systems were dynamically sampled by introducing fictitious moments as in the PIMD based on the standard primitive approximation. The indistinguishability of the particles was handled by a pseudopotential of particle permutation that is an extension of our previous one [J. Chem. Phys. 112, 10 116 (2000)]. As a test of our methodology for Boltzmann statistics, calculations have been performed for liquid helium-4 at 4 K. We found that the PIMD with the pair density matrix approximation dramatically reduced the computational cost to obtain the structural as well as dynamical (using the centroid molecular dynamics approximation) properties at the same level of accuracy as that with the primitive approximation. With respect to the identical particles, we performed the calculation of a bosonic triatomic cluster. Unlike the primitive approximation, the pseudopotential scheme based on the pair density matrix approximation described well the bosonic correlation among the interacting atoms. Convergence with a small number of discretization of the path achieved by this approximation enables us to construct a method of avoiding the problem of the vanishing pseudopotential encountered in the calculations by the primitive approximation.
机译:在本文中,路径积分分子动力学(PIMD)方法已被扩展为采用对路径作用的有效近似,即对密度矩阵近似。同构经典系统的配置是通过引入虚拟矩来动态采样的,就像在PIMD中基于标准原始近似法一样。粒子的不可区分性通过粒子置换的伪势来处理,该伪势是我们先前粒子的伪势的扩展。化学物理112,10 116(2000)]。作为对我们的Boltzmann统计方法的测试,已经对4 K下的液态氦4进行了计算。我们发现,具有对密度矩阵近似的PIMD显着降低了获得结构和动力学(使用质心分子动力学近似)属性具有与原始近似相同的精度水平。对于相同的粒子,我们进行了玻色三原子团簇的计算。与原始近似不同,基于对密度矩阵近似的伪势方案很好地描述了相互作用原子之间的玻色相关性。通过该近似实现的路径的少量离散化的收敛,使我们能够构造一种方法,从而避免通过原始近似而避免在计算中遇到的伪电位消失的问题。

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