fix bug

Author: haozhihan

source/module_hsolver/hsolver_pw.h

@@ -84,6 +84,8 @@ class HSolverPW
     int rank_in_pool = 0;
     int nproc_in_pool = 1;
 
+    std::vector<double> ethr_band;
+
   private:
     /// @brief calculate the threshold for iterative-diagonalization for each band
     void cal_ethr_band(const double& wk, const double* wg, const double& ethr, std::vector<double>& ethrs);