diff --git a/source/source_pw/module_pwdft/soc.cpp b/source/source_pw/module_pwdft/soc.cpp
index a44a0b6a48f..574a31a834a 100644
--- a/source/source_pw/module_pwdft/soc.cpp
+++ b/source/source_pw/module_pwdft/soc.cpp
@@ -28,6 +28,19 @@ void Fcoef::create(const int i1, const int i2, const int i3)
     else
     {
         std::cout << "not allowed!" << std::endl;
+        if (!(i1 * i2 * i3 > 0)){
+            std::cout << "i1*i2*i3 must be positive! i1*i2*i3 is " << i1 * i2 * i3 << std::endl;
+        }
+        if (!(i1 > 0)){
+            std::cout << "i1 must be positive! i1 is " << i1 << std::endl;
+        }
+        if (!(i2 > 0)){
+            std::cout << "i2 must be positive! i2 is " << i2 << std::endl;
+        }
+        if (!(i3 > 0)){
+            std::cout << "i3 must be positive! i3 is " << i3 << std::endl;
+        }
+
     }
 
     return;