An improved fast multipole method for electrostatic potential calculations in a class of coarse-grained molecular simulations
- Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, AZ 85721 (United States)
- Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute (RPI), Troy, NY 12180 (United States)
This paper presents a novel algorithm to approximate the long-range electrostatic potential field in the Cartesian coordinates applicable to 3D coarse-grained simulations of biopolymers. In such models, coarse-grained clusters are formed via treating groups of atoms as rigid and/or flexible bodies connected together via kinematic joints. Therefore, multibody dynamic techniques are used to form and solve the equations of motion of such coarse-grained systems. In this article, the approximations for the potential fields due to the interaction between a highly negatively/positively charged pseudo-atom and charged particles, as well as the interaction between clusters of charged particles, are presented. These approximations are expressed in terms of physical and geometrical properties of the bodies such as the entire charge, the location of the center of charge, and the pseudo-inertia tensor about the center of charge of the clusters. Further, a novel substructuring scheme is introduced to implement the presented far-field potential evaluations in a binary tree framework as opposed to the existing quadtree and octree strategies of implementing fast multipole method. Using the presented Lagrangian grids, the electrostatic potential is recursively calculated via sweeping two passes: assembly and disassembly. In the assembly pass, adjacent charged bodies are combined together to form new clusters. Then, the potential field of each cluster due to its interaction with faraway resulting clusters is recursively calculated in the disassembly pass. The method is highly compatible with multibody dynamic schemes to model coarse-grained biopolymers. Since the proposed method takes advantage of constant physical and geometrical properties of rigid clusters, improvement in the overall computational cost is observed comparing to the tradition application of fast multipole method.
- OSTI ID:
- 22314885
- Journal Information:
- Journal of Computational Physics, Vol. 270; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9991
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
ALGORITHMS
APPROXIMATIONS
ATOMS
CARTESIAN COORDINATES
CHARGED PARTICLES
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
ELECTRIC POTENTIAL
ELECTROSTATICS
EQUATIONS OF MOTION
LAGRANGIAN FUNCTION
MOLECULAR DYNAMICS METHOD
MOMENT OF INERTIA
POTENTIALS
TENSORS