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1.1.4. Per-atom properties
This section documents the following functions:
-
int lammps_extract_atom_datatype(void *handle, const char *name)
Get data type of a LAMMPS per-atom property
New in version 18Sep2020.
This function returns an integer that encodes the data type of the per-atom property with the specified name. See
_LMP_DATATYPE_CONST
for valid values. Callers oflammps_extract_atom()
can use this information to then decide how to cast thevoid *
pointer and access the data.- Parameters:
handle – pointer to a previously created LAMMPS instance
name – string with the name of the extracted property
- Returns:
integer constant encoding the data type of the property or -1 if not found.
-
void *lammps_extract_atom(void *handle, const char *name)
Get pointer to a LAMMPS per-atom property.
This function returns a pointer to the location of per-atom properties (and per-atom-type properties in the case of the ‘mass’ keyword). Per-atom data is distributed across sub-domains and thus MPI ranks. The returned pointer is cast to
void *
and needs to be cast to a pointer of data type that the entity represents.A table with supported keywords is included in the documentation of the
Atom::extract()
function.Warning
The pointers returned by this function are generally not persistent since per-atom data may be re-distributed, re-allocated, and re-ordered at every re-neighboring operation.
- Parameters:
handle – pointer to a previously created LAMMPS instance
name – string with the name of the extracted property
- Returns:
pointer (cast to
void *
) to the location of the requested data orNULL
if not found.