Phonon absorbing boundary conditions for molecular dynamics

  • Authors:

  • Murthy N. Guddati;Senganal Thirunavukkarasu

  • Affiliations:

  • Department of Civil Engineering, North Carolina State University, Raleigh, NC 27695-7908, USA;Department of Civil Engineering, North Carolina State University, Raleigh, NC 27695-7908, USA

  • Venue:
  • Journal of Computational Physics
  • Year:
  • 2009

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Abstract

With the goal of minimizing the domain size for molecular dynamics (MD) simulations, we develop a new class of absorbing boundary conditions (ABCs) that mimic the phonon absorption properties of an unbounded exterior. The proposed MD-ABCs are extensions of perfectly matched discrete layers (PMDLs), 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 paper 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 MD-ABCs, MD-PMDL is local in both space and time and thus more efficient. Based on their favorable properties, it is concluded that MD-PMDL could provide a more effective alternative to existing MD-ABCs.