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Re: [lammps-users] definition of map file format
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Re: [lammps-users] definition of map file format

From: Axel Kohlmeyer <akohlmey@...24...>
Date: Sat, 18 Nov 2017 09:44:56 -0500

On Fri, Nov 17, 2017 at 2:31 PM, Zbigniew Koziol <softquake@...24...> wrote:
Is there anywhere a formal definition of map_file format? It is used for instance by fix phonon. I know, you may tell me that I can guess myself. And I am close to that. Anyway, if it was around why should I waste my time? And others would jump more easy into all that where map file could be used.

​rather than telling you to guess, i would suggest to read the manual as the much more reliable option. from the fix phonon​ docs (in the original docs, "latgen" links to a repository for a software generating the map file):

The map_file contains the mapping information between the lattice indices and the atom IDs, which tells the code which atom sits at which lattice point; the lattice indices start from 0. An auxiliary code, latgen, can be employed to generate the compatible map file for various crystals.

In case one simulates an aperiodic system, where the whole simulation box is treated as a unit cell, one can set map_file as GAMMA, so that the mapping info will be generated internally and a file is not needed. In this case, the dynamical matrix at only the gamma-point will/can be evaluated. Please keep in mind that fix-phonon is designed for cyrstals, it will be inefficient and even degrade the performance of lammps in case the unit cell is too large.



Zbigniew Kozioł, PhD,
National Center for Nuclear Research,
Materials Research Laboratory,
ul. Andrzeja Sołtana 7,
05-400 Otwock-Świerk, Poland
mobile: +48 507 330 216

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Dr. Axel Kohlmeyer  akohlmey@...24...
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.