Feature: change the default value of ecutwfc based on basis_type (#5390)

* revalue ecutwfc by basis_type and add a check

* add some comments

* update the docs

Author: WHUweiqingzhou

docs/advanced/input_files/input-main.md

@@ -728,7 +728,7 @@ These variables are used to control the plane wave related parameters.
 
 - **Type**: Real
 - **Description**: Energy cutoff for plane wave functions, the unit is **Rydberg**. Note that even for localized orbitals basis, you still need to setup an energy cutoff for this system. Because our local pseudopotential parts and the related force are calculated from plane wave basis set, etc. Also, because our orbitals are generated by matching localized orbitals to a chosen set of wave functions from a certain energy cutoff, this set of localize orbitals is most accurate under this same plane wave energy cutoff.
-- **Default**: 50
+- **Default**: 50 Ry (PW basis), 100 Ry (LCAO basis)
 
 ### ecutrho
 

source/module_io/read_input_item_system.cpp

@@ -262,6 +262,24 @@ void ReadInput::item_system()
         Input_Item item("ecutwfc");
         item.annotation = "energy cutoff for wave functions";
         read_sync_double(input.ecutwfc);
+        item.reset_value = [](const Input_Item& item, Parameter& para) {
+            if (para.input.ecutwfc == 0){ // 0 means no input value
+                if (para.input.basis_type == "lcao")
+                {
+                    para.input.ecutwfc = 100;
+                }
+                else
+                {
+                    para.input.ecutwfc = 50;
+                }
+            }
+        };
+        item.check_value = [](const Input_Item& item, const Parameter& para) {
+            if (para.input.ecutwfc <= 0)
+            {
+                ModuleBase::WARNING_QUIT("ReadInput", "ecutwfc should be positive");
+            }
+        };
         this->add_item(item);
     }
     {

source/module_parameter/input_parameter.h

@@ -33,7 +33,7 @@ struct Input_para
     int kpar = 1;                   ///< ecch pool is for one k point
     int bndpar = 1;                 ///< parallel for stochastic/deterministic bands
     std::string latname = "none";   ///< lattice name
-    double ecutwfc = 50;            ///< energy cutoff for wavefunctions
+    double ecutwfc = 0;            ///< energy cutoff for wavefunctions
     double ecutrho = 0;             ///< energy cutoff for charge/potential
 
     int nx = 0, ny = 0, nz = 0;    ///< three dimension of FFT wavefunc