Reorder lammps layered dihedrals, and accurately count duplicated dih…

…edrals in the header n_dihedrals for dihedrals that are counted twice due to multiple layers of the dihedral

gmso/formats/lammpsdata.py

@@ -34,9 +34,6 @@
 from gmso.utils.units import LAMMPS_UnitSystems, write_out_parameter_and_units
 
 
-# TODO: impropers have to read multiple terms for each improper
-# TODO: speed up this function to handle 500000 atoms
-# TODO: make every parameter source identify styles
 # TODO: Write in header of each potential type any conversions that happened
 # TODO: write in file header the source of the xml
 @saves_as(".lammps", ".lammpsdata", ".data")
@@ -725,10 +722,11 @@ def _validate_unit_compatibility(top, base_unyts):
 def _write_header(out_file, top, atom_style, dihedral_parser):
     """Write Lammps file header."""
     out_file.write(
-        "{} written by {} at {} using the GMSO LAMMPS Writer\n\n".format(
+        "{} written by {} at {} using the GMSO LAMMPS Writer\nUsing Forcefield {}\n\n".format(
             os.environ.get("USER"),
             top.name if top.name is not None else "",
             str(datetime.datetime.now()),
+            top.get_forcefield().name,
         )
     )
     out_file.write("{:d} atoms\n".format(top.n_sites))

gmso/tests/files/charmm.lammps

@@ -1,4 +1,5 @@
 calcraven written by Topology at 2023-12-07 19:10:26.697824 using the GMSO LAMMPS Writer
+Using Forcefield Topology_ForceField
 
 9 atoms
 8 bonds

gmso/tests/test_lammps.py

@@ -34,10 +34,14 @@ def compare_lammps_files(fn1, fn2, skip_linesList=[], offsets=None):
     line_counter2 = 0
     while True:
         # check for offsets
-        if offsets:
-            if offsets[0][0][0] == line_counter1:
+        if offsets is not None:
+            if len(offsets[0]) == 0:
+                pass
+            elif offsets[0][0][0] == line_counter1:
                 line_counter1 += offsets[0][0][1]
                 offsets[0].pop(0)
+            if len(offsets[1]) == 0:
+                pass
             elif offsets[1][0][0] == line_counter2:
                 line_counter2 += offsets[1][0][1]
                 offsets[1].pop(0)
@@ -294,6 +298,7 @@ def test_lammps_vs_parmed_by_mol(self, top, request):
             "gmso.lammps",
             "pmd.lammps",
             skip_linesList=[0],
+            offsets=[[[1, 1], ["none", "none"]], [["none", "none"]]],
         )
 
     @pytest.mark.parametrize(
@@ -325,6 +330,7 @@ def test_lammps_vs_parmed_by_styles(
             "gmso.lammps",
             "pmd.lammps",
             skip_linesList=[0],
+            offsets=[[[0, 1]], [["none", "none"]]],
         )
 
     def test_lammps_default_conversions(
@@ -343,7 +349,7 @@ def test_lammps_default_conversions(
         typed_ethane.save("opls.lammps")
         with open("opls.lammps", "r") as f:
             lines = f.readlines()
-        assert lines[38:41] == [
+        assert lines[39:42] == [
             "Dihedral Coeffs #OPLSTorsionPotential\n",
             "#\tk1 (kcal/mol)\tk2 (kcal/mol)\tk3 (kcal/mol)\tk4 (kcal/mol)\n",
             "1\t0.000000\t-0.000000\t0.300000\t-0.000000\t# opls_140\topls_135\topls_135\topls_140\n",
@@ -361,7 +367,7 @@ def test_lammps_default_conversions(
             "gmso.lammps",
             "pmd.lammps",
             skip_linesList=[0],
-            offsets=[[[16, 1], ["none", "none"]], [["none", "none"]]],
+            offsets=[[[0, 1], [17, 1]], []],
         )
         out_lammps = open("gmso.lammps", "r").readlines()
         found_impropers = False