\(\renewcommand{\AA}{\text{Å}}\)
2.3.6. System properties
Similar to what is described in System properties, the instances of
lammps
can be used to extract different kinds
of information about the active LAMMPS instance and also to modify some of it.
In some cases the data returned is a direct reference to the original data
inside LAMMPS cast to ctypes
pointers. Where possible, the wrappers will
determine the ctypes
data type and cast pointers accordingly. If
numpy
is installed arrays can also be extracted as numpy arrays, which
will access the C arrays directly and have the correct dimensions to protect
against invalid accesses.
Warning
When accessing per-atom data, please note that this data is the per-processor local data and indexed accordingly. These arrays can change sizes and order at every neighbor list rebuild and atom sort event as atoms are migrating between subdomains.
from lammps import lammps
lmp = lammps()
lmp.file("in.sysinit")
natoms = lmp.get_natoms()
print(f"running simulation with {natoms} atoms")
lmp.command("run 1000 post no");
for i in range(10):
lmp.command("run 100 pre no post no")
pe = lmp.get_thermo("pe")
ke = lmp.get_thermo("ke")
print(f"PE = {pe}\nKE = {ke}")
lmp.close()
Methods:
version()
: return the numerical version id, e.g. LAMMPS 2 Sep 2015 -> 20150902get_thermo()
: return current value of a thermo keywordlast_thermo()
: return a dictionary of the last thermodynamic outputget_natoms()
: total # of atoms as intreset_box()
: reset the simulation box sizeextract_setting()
: return a global settingextract_global()
: extract a global quantityextract_box()
: extract box infocreate_atoms()
: create N atoms with IDs, types, x, v, and image flags
Properties:
last_thermo_step
: the last timestep thermodynamic output was computed