fix: psi error for large system (#6501)

* fix: psi error

* fix: type of psi_bias

---------

Co-authored-by: dyzheng <[email protected]>

Author: dyzheng

source/source_psi/psi.cpp

@@ -301,7 +301,7 @@ const int* Psi<T, Device>::get_ngk_pointer() const
 }
 
 template <typename T, typename Device>
-const int& Psi<T, Device>::get_psi_bias() const
+const size_t& Psi<T, Device>::get_psi_bias() const
 {
     return this->psi_bias;
 }

source/source_psi/psi.h

@@ -130,7 +130,7 @@ class Psi
     const Device* get_device() const;
 
     // return psi_bias
-    const int& get_psi_bias() const;
+    const size_t& get_psi_bias() const;
 
     const int& get_current_ngk() const;
 
@@ -156,7 +156,7 @@ class Psi
     // current pointer for getting the psi
     mutable T* psi_current = nullptr;
     // psi_current = psi + psi_bias;
-    mutable int psi_bias = 0;
+    mutable size_t psi_bias = 0;
 
     const int* ngk = nullptr;