Allow for float ENCUTs in Wavecar class

pymatgen/io/vasp/outputs.py

@@ -4849,7 +4849,8 @@ def __init__(self, filename="WAVECAR", verbose=False, precision="normal", vasp_t
             np.fromfile(f, dtype=np.float64, count=(recl8 - 3))
 
             # extract kpoint, bands, energy, and lattice information
-            self.nk, self.nb, self.encut = np.fromfile(f, dtype=np.float64, count=3).astype(int)
+            self.nk, self.nb = np.fromfile(f, dtype=np.float64, count=2).astype(int)
+            self.encut = np.fromfile(f, dtype=np.float64, count=1)[0]
             self.a = np.fromfile(f, dtype=np.float64, count=9).reshape((3, 3))
             self.efermi = np.fromfile(f, dtype=np.float64, count=1)[0]
             if verbose:

pymatgen/io/vasp/tests/test_outputs.py

@@ -1785,6 +1785,7 @@ def setUp(self):
         self.wH2 = Wavecar(self.TEST_FILES_DIR / "WAVECAR.H2_low_symm")
         self.wH2_gamma = Wavecar(self.TEST_FILES_DIR / "WAVECAR.H2_low_symm.gamma")
         self.w_ncl = Wavecar(self.TEST_FILES_DIR / "WAVECAR.H2.ncl")
+        self.w_frac_encut = Wavecar(self.TEST_FILES_DIR / "WAVECAR.frac_encut")
 
     def test_standard(self):
         w = self.w
@@ -1801,7 +1802,7 @@ def test_standard(self):
 
         self.assertEqual(w.filename, self.TEST_FILES_DIR / "WAVECAR.N2")
         self.assertAlmostEqual(w.efermi, -5.7232, places=4)
-        self.assertEqual(w.encut, 25)
+        self.assertEqual(w.encut, 25.0)
         self.assertEqual(w.nb, 9)
         self.assertEqual(w.nk, 1)
         self.assertTrue(np.allclose(w.a, a))
@@ -1817,6 +1818,10 @@ def test_standard(self):
             for b in range(w.nb):
                 self.assertEqual(len(w.coeffs[k][b]), len(w.Gpoints[k]))
 
+        # Test WAVECAR with fractional encut
+        self.assertEqual(self.w_frac_encut.encut, 100.5)
+
+        # Test malformed WAVECARs
         with self.assertRaises(ValueError):
             Wavecar(self.TEST_FILES_DIR / "WAVECAR.N2.malformed")
 
@@ -1845,7 +1850,7 @@ def test_n2_45210(self):
         w = Wavecar(self.TEST_FILES_DIR / "WAVECAR.N2.45210")
         self.assertEqual(w.filename, self.TEST_FILES_DIR / "WAVECAR.N2.45210")
         self.assertAlmostEqual(w.efermi, -5.7232, places=4)
-        self.assertEqual(w.encut, 25)
+        self.assertEqual(w.encut, 25.0)
         self.assertEqual(w.nb, 9)
         self.assertEqual(w.nk, 1)
         self.assertTrue(np.allclose(w.a, self.a))