Fix: bug when nspin = 2, fixed smearing

docs/advanced/input_files/input-main.md

@@ -882,7 +882,7 @@ calculations.
 
 - **Type**: String
 - **Description**: It indicates which occupation and smearing method is used in the calculation.
-  - **fixed**: fixed occupations.
+  - **fixed**: fixed occupations (available for non-coductors only)
   - **gauss** or **gaussian**: Gaussian smearing method.
   - **mp**: methfessel-paxton smearing method; recommended for metals.
   - **fd**: Fermi-Dirac smearing method: $f=1/\{1+\exp[(E-\mu)/kT]\}$ and smearing_sigma below is the temperature $T$ (in Ry).

source/module_elecstate/occupy.cpp

@@ -131,8 +131,12 @@ void Occupy::iweights(const int nks,
                       const std::vector<int>& isk)
 {
     assert(is < 2);
+    double degspin = 2.0;
+    if (GlobalV::NSPIN == 4)
+        degspin = 1.0;
+    if (is != -1)
+        degspin = 1.0;
 
-    double degspin = (GlobalV::NSPIN == 1) ? 2.0 : 1.0;
     double ib_mind = nelec / degspin;
     int ib_min = std::ceil(ib_mind);
     if (ib_min != int(ib_mind))

source/module_elecstate/test/elecstate_occupy_test.cpp

@@ -225,7 +225,7 @@ TEST_F(OccupyTest, IweightsWarning)
   ekb(0, 0) = 0.1;
 
   testing::internal::CaptureStdout();
-  EXPECT_EXIT(occupy.iweights(1, wk, 1, 1.0, ekb, ef, wg, 0, isk);, ::testing::ExitedWithCode(0), "");
+  EXPECT_EXIT(occupy.iweights(1, wk, 1, 1.0, ekb, ef, wg, -1, isk);, ::testing::ExitedWithCode(0), "");
   output = testing::internal::GetCapturedStdout();
   EXPECT_THAT(output, testing::HasSubstr("It is not a semiconductor or insulator. Change 'smearing_method'."));
 }