fix on reading multiple route in Gaussian input file (#2939)

* fixed reading multiple route in gaussian input

* add test for multiple lines of route

* fixed test

* code style

---------

Co-authored-by: Janosh Riebesell <[email protected]>

Author: Ameyanagi

pymatgen/io/gaussian.py

@@ -313,6 +313,9 @@ def from_string(contents):
             # This condition allows for route cards spanning multiple lines
             elif (line == "" or line.isspace()) and route_index:
                 break
+            if route_index:
+                route += f" {line}"
+                route_index = idx
         functional, basis_set, route_paras, dieze_tag = read_route_line(route)
         ind = 2
         title = []

pymatgen/io/tests/test_gaussian.py

@@ -127,6 +127,7 @@ def test_from_string(self):
         gau_str = """%mem=5000000
         %chk=filename
         # mp2/6-31g* scf=direct
+        opt freq
 
         SIH4+ H2---SIH2+ CS //MP2(full)/6-31G* MP2=-290.9225259
 
@@ -149,6 +150,7 @@ def test_from_string(self):
 
         gau = GaussianInput.from_string(gau_str)
         assert gau.molecule.composition.reduced_formula == "X3SiH4"
+        assert set(gau.route_parameters) == {"opt", "freq", "scf"}
 
     def test_gen_basis(self):
         gau_str = """#N B3LYP/Gen Pseudo=Read