mirror of https://github.com/lammps/lammps.git
80 lines
1.7 KiB
Python
Executable File
80 lines
1.7 KiB
Python
Executable File
#!/usr/bin/env python -i
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# preceeding line should have path for Python on your machine
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# split.py
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# Purpose: similar to simple.py, but first the world communicator
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# is split in two halves and LAMMPS is run only on one partition
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# Syntax: split.py in.lammps
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# in.lammps = LAMMPS input script
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import sys
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# parse command line
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argv = sys.argv
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if len(argv) != 2:
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print "Syntax: simple.py in.lammps"
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sys.exit()
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infile = sys.argv[1]
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me = 0
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# this example *only* works with mpi4py version 2.0.0 or later
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from mpi4py import MPI
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comm = MPI.COMM_WORLD
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me = comm.Get_rank()
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nprocs = comm.Get_size()
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# create two subcommunicators
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if me < nprocs // 2: color = 0
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else: color = 1
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split = comm.Split(color,key=0)
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if color == 0:
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from lammps import lammps
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lmp = lammps(comm=split)
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# run infile one line at a time
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lines = open(infile,'r').readlines()
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for line in lines: lmp.command(line)
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# run 10 more steps
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# get coords from LAMMPS
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# change coords of 1st atom
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# put coords back into LAMMPS
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# run a single step with changed coords
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lmp.command("run 10")
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x = lmp.gather_atoms("x",1,3)
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epsilon = 0.1
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x[0] += epsilon
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lmp.scatter_atoms("x",1,3,x)
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lmp.command("run 1");
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f = lmp.extract_atom("f",3)
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print "Force on 1 atom via extract_atom: ",f[0][0]
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fx = lmp.extract_variable("fx","all",1)
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print "Force on 1 atom via extract_variable:",fx[0]
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print "Proc %d out of %d procs has" % (me,nprocs), lmp
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print "Calculation on partition 0 complete"
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else:
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# could run a 2nd calculation on second partition
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# with different LAMMPS instance or another code
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# in this case, just sleep on second partition
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import time
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time.sleep(2)
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print "Calculation on partition 1 complete"
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# shutdown mpi4py
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comm.Barrier()
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MPI.Finalize()
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