Absorbing Boundary Conditions for Molecular Dynamics

molecular dynamics;wave propagation in discrete systems;absorbing boundary conditions

Thirunavukkarasu, Senganal ; Dr. M. N. Guddati, Committee Chair,Dr. P. A. Gremaud, Committee Member,Dr. M. S. Rahman, Committee Member,Thirunavukkarasu, Senganal ; Dr. M. N. Guddati ; Committee Chair ; Dr. P. A. Gremaud ; Committee Member ; Dr. M. S. Rahman ; Committee Member

University:North Carolina State University

关键词: molecular dynamics;    wave propagation in discrete systems;    absorbing boundary conditions;   

Others  :  https://repository.lib.ncsu.edu/bitstream/handle/1840.16/1880/etd.pdf?sequence=1&isAllowed=y

美国|英语

来源: null

【 摘 要 】

With the goal of minimizing the domain size for Molecular dynamics (MD) simulations, we develop a new class of absorbing boundary conditions (MD-ABC's) that can mimic the phonon absorption of an unbounded exterior. The proposed MD-ABC's are extensions of perfectly matched discrete layers (PMDL), originally developed as an absorbing boundary condition for continuous wave propagation problems. Called MD-PMDL, this extension carefully targets the absorption of phonons, the high frequency waves, whose propagation properties are completely different from continuous waves.This thesis presents the derivation of MD-PMDL for general lattice systems, followed by explicit application to one-dimensional and two-dimensional square lattice systems.The accuracy of MD-PMDL for phonon absorption is proven by analyzing reflection coefficients, and demonstrated through numerical experiments. Unlike existing ABC's that are effective for high frequency phonon absorption, MD-PMDL is local in both space and time and is thus more efficient. Based on their favorable properties, it is concluded that MD-PMDL could provide a more effective alternative to existing MD-ABC's.