Title: A new method for calculating the pressure profile by LAMMPS

Presenter: Takenobu Nakamura

Affiliation: Tohoku University WPI-AIMR

Abstract: Different from density or kinetic energy, the computation for local pressure tensor has not been supported by LAMMPS. That is partly because the local pressure tensor is not defined as a “per-atom” quantity but as a result of an interaction among several atoms in a cluster potential. According to the literature 1, the local pressure tensor can be explicitly represented by using a contour integration. Using the representation, we have developed a method to calculate the local pressure tensor along the radial axis for a spherical material 2. Additionally, we have recently developed a method for calculating the 3-dimensional local pressure tensor with high accuracy 3. Our method exactly assigns the contribution of contour integration to each 3D bin without a numerical approximation as in the previous method 4. We have made a new command calculating local pressure field for (1) cuboids divided in a 3 dimensional grid pattern, (2) planar bins sliced along 1 dimensional axis 5, (3) spherical bins sliced along the radial axis from a chosen center. In this talk, after a brief introduction of the theoretical background of the method, we will demonstrate a few application studies. We also show how to use the method in lammps.

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2 T. Nakamura, W. Shinoda and T. Ikeshoji, J. Chem. Phys. 135, 094106 (2011).

3 T. Nakamura, S. Kawamoto and W. Shionda in preparation (2013)

4 O. H. S. Ollila, H. J. Risselada, M. Louhivuori, E. Lindahl, I. Vattulainen, and S. J. Marrink, Phys. Rev. Lett. 102, 078101 (2009).

5 E. Lindahl and O. Edholm, J. Chem. Phys. 113, 3882 (2000).