37 lines
1.3 KiB
Python
37 lines
1.3 KiB
Python
# this example requires the LAMMPS Python package (lammps.py) to be installed
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# and LAMMPS to be loadable as shared library in LD_LIBRARY_PATH
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import lammps
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def callback(caller, ntimestep, nlocal, tag, x, fext):
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"""
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This callback receives a caller object that was setup when registering the callback
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In addition to timestep and number of local atoms, the tag and x arrays are passed as
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NumPy arrays. The fext array is a force array allocated for fix external, which
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can be used to apply forces to all atoms. Simply update the value in the array,
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it will be directly written into the LAMMPS C arrays
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"""
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print("Data passed by caller (optional)", caller)
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print("Timestep:", ntimestep)
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print("Number of Atoms:", nlocal)
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print("Atom Tags:", tag)
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print("Atom Positions:", x)
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print("Force Additions:", fext)
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fext.fill(1.0)
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print("Force additions after update:", fext)
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print("="*40)
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L = lammps.lammps()
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L.file("in.lammps")
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# you can pass an arbitrary Python object to the callback every time it is called
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# this can be useful if you need more state information such as the LAMMPS ptr to
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# make additional library calls
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custom_object = ["Some data", L]
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L.set_fix_external_callback("2", callback, custom_object)
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L.command("run 100")
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