Refactor and Fix Parallel Handling of Plane Wave Counts in Eigenvalue Output (#6844)

* remove dependency on shell

* fix compile error

* fix gtest error

* fix system call in the gtest

* fix MPI error

* reset test

* delete useless code

Author: A-006

source/source_io/write_eig_occ.cpp

@@ -20,13 +20,6 @@ void ModuleIO::write_eig_iter(const ModuleBase::matrix &ekb,const ModuleBase::ma
     const int nspin = PARAM.inp.nspin;
     const int nks = kv.get_nks();
 	const int nkstot = kv.get_nkstot();
-
-    std::vector<int> ngk_tot = kv.ngk;
-
-#ifdef __MPI
-    MPI_Allreduce(MPI_IN_PLACE, ngk_tot.data(), nks, MPI_INT, MPI_SUM, POOL_WORLD);
-#endif
-
     const int nk_fac = nspin == 2 ? 2 : 1;
     const int nks_np = nks / nk_fac;
     const int nkstot_np = nkstot / nk_fac;
@@ -205,11 +198,10 @@ void ModuleIO::write_eig_file(const ModuleBase::matrix &ekb,
     {
         ModuleBase::WARNING_QUIT("ModuleIO::write_eig_file", "Eigenvalues are too large!");
     }
-
     std::vector<int> ngk_tot = kv.ngk;
-
 #ifdef __MPI
-    MPI_Allreduce(MPI_IN_PLACE, ngk_tot.data(), nks, MPI_INT, MPI_SUM, POOL_WORLD);
+    std::vector<int> send_ngk_tot = kv.ngk;
+    MPI_Allreduce(send_ngk_tot.data(), ngk_tot.data(), nks, MPI_INT, MPI_SUM, POOL_WORLD);
 #endif    
 
     // file name to store eigenvalues