fix bug

Author: haozhihan

source/module_psi/psi.cpp

@@ -240,7 +240,7 @@ template <typename T, typename Device>
 template <typename T_in, typename Device_in>
 Psi<T, Device>::Psi(const Psi<T_in, Device_in>& psi_in)
 {
-    this->ngk = psi_in.ngk;
+    this->ngk = psi_in.get_ngk_pointer();
     this->npol = psi_in.npol;
     this->nk = psi_in.get_nk();
     this->nbands = psi_in.get_nbands();
@@ -332,6 +332,12 @@ const Device* Psi<T, Device>::get_device() const
     return this->ctx;
 }
 
+template <typename T, typename Device>
+const int* Psi<T, Device>::get_ngk_pointer() const
+{
+    return this->ngk;
+}
+
 template <typename T, typename Device>
 const int& Psi<T, Device>::get_psi_bias() const
 {

source/module_psi/psi.h

@@ -124,6 +124,8 @@ class Psi
 
     const int& get_ngk(const int ik_in) const;
 
+    const int* get_ngk_pointer() const;
+
     // return k_first
     const bool& get_k_first() const;