forked from lijiext/lammps
65 lines
2.4 KiB
Plaintext
65 lines
2.4 KiB
Plaintext
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This directory has an application that runs classical MD via LAMMPS,
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but uses quantum forces calculated by the Quest DFT (density
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functional) code in place of the usual classical MD forces calculated
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by a pair style in LAMMPS.
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lmpqst.cpp main program
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it links LAMMPS as a library
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it invokes Quest as an executable
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in.lammps LAMMPS input script, without the run command
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si_111.in Quest input script for an 8-atom Si unit cell
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lmppath.h contains path to LAMMPS home directory
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qstexe.h contains full pathname to Quest executable
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After editing the Makefile, lmppath.h, and qstexe.h to make them
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suitable for your box, type:
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g++ -f Makefile.g++
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and you should get the lmpqst executable.
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NOTE: To run this coupled application, you must of course, have Quest
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built on your system. It's WWW site is http://dft.sandia.gov/Quest.
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It is not an open-source code, buy you can contact its authors to
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obtain a copy.
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You can run lmpqst in serial or parallel as:
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% lmpqst Niter in.lammps in.quest
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% mpirun -np 4 lmpqst Niter in.lammps in.quest
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where
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Niter = # of MD iterations
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in.lammps = LAMMPS input script
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in.quest = Quest input script
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The log files are for this run:
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% lmpqst 10 in.lammps si_111.in
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This application is an example of a coupling where the driver code
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(lmpqst) runs one code (LAMMPS) as an outer code and facilitates it
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calling the other code (Quest) as an inner code. Specifically, the
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driver (lmpqst) invokes one code (LAMMPS) to perform its timestep
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loop, and grabs information from the other code (Quest) during its
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timestep. This is done in LAMMPS using the fix external command,
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which makes a "callback" to the driver application (lmpqst), which in
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turn invokes Quest with new atom coordinates, lets Quest compute
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forces, and returns those forces to the LAMMPS fix external.
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The driver code launches LAMMPS in parallel. But Quest is only run on
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a single processor. It would be possible to change this by using a
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parallel build of Quest.
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Since Quest does not currently have a library interface, the driver
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code interfaces with Quest via input and output files.
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Note that essentially 100% of the run time for this coupled
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application is spent in Quest, as the quantum calculation of forces
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dominates the calculation.
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You can look at the log files in the directory to see sample LAMMPS
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output for this simulation. Dump files produced by LAMMPS are stored
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as dump.md.
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