Add some user-defined parameters

Docs/source/running_cpp/parameters.rst

@@ -1051,6 +1051,15 @@ Numerics and algorithms
     The conductivity, permittivity, and permeability of the computational medium, respectively.
     If ``algo.em_solver_medium`` is set to macroscopic, then these properties must be provided.
 
+* ``macroscopic.mag_normalized_error`` (`double`; default: `0.1`)
+    The maximum relative amount we let M deviate from Ms before aborting for the LLG equation. This requires `USE_LLG=TRUE` in the GNUMakefile.
+
+* ``macroscopic.mag_max_iter`` (`int`; default: `100`)
+    The maximum number of iterations allowed of the 2nd-order trapezoidal scheme for the LLG equation. This requires `USE_LLG=TRUE` in the GNUMakefile.
+
+* ``macroscopic.mag_tol`` (`double`; default: `0.0001`)
+    The relative tolerance stopping criteria for 2nd-order iterative algorithm of the 2nd-order trapezoidal scheme for the LLG equation. This requires `USE_LLG=TRUE` in the GNUMakefile.
+
 * ``warpx.mag_time_scheme_order`` (`1` or `2`; default: `1`)
     The value of the time advancement scheme of M field. `mag_time_scheme_order==1` is the 1st-order Eulerian scheme and `mag_time_scheme_order==2` is the 2nd-order trapezoidal scheme for the LLG equation. This requires `USE_LLG=TRUE` in the GNUMakefile.
 

Source/FieldSolver/FiniteDifferenceSolver/MacroscopicEvolveM.cpp

@@ -43,8 +43,9 @@ void FiniteDifferenceSolver::MacroscopicEvolveM (
         amrex::Real const dt,
         std::unique_ptr<MacroscopicProperties> const& macroscopic_properties )
     {
-    // Temporary value hard-coded for normalized error used for LLG.
-    amrex::Real mag_normalized_error = 0.1_rt; // normalization error of M field for checking
+
+        // obtain the maximum relative amount we let M deviate from Ms before aborting
+        amrex::Real mag_normalized_error = macroscopic_properties->getmag_normalized_error();
 
         for (MFIter mfi(*Mfield[0], TilingIfNotGPU()); mfi.isValid(); ++mfi) /* remember to FIX */
         {

Source/FieldSolver/FiniteDifferenceSolver/MacroscopicEvolveM_2nd.cpp

@@ -282,10 +282,11 @@ void FiniteDifferenceSolver::MacroscopicEvolveM_2nd (
         }
 
         // initialize M_max_iter, M_iter, M_tol, M_iter_error
-        // change these to user-defined input in the next PR
-        int M_max_iter = 100;
+        // maximum number of iterations allowed
+        int M_max_iter = macroscopic_properties->getmag_max_iter();
         int M_iter = 0;
-        amrex::Real M_tol = 0.0001;
+        // relative tolerance stopping criteria for 2nd-order iterative algorithm
+        amrex::Real M_tol = macroscopic_properties->getmag_tol();
         amrex::Real M_iter_maxerror = -1.0;
         int stop_iter = 0;
 

Source/FieldSolver/FiniteDifferenceSolver/MacroscopicProperties/MacroscopicProperties.H

@@ -47,6 +47,10 @@ public:
      amrex::MultiFab& getmag_alpha_mf () {return (*m_mag_alpha_mf);}
      amrex::MultiFab& getmag_gamma_mf () {return (*m_mag_gamma_mf);}
 
+     amrex::Real getmag_normalized_error () {return m_mag_normalized_error;}
+     int getmag_max_iter () {return m_mag_max_iter;}
+     amrex::Real getmag_tol () {return m_mag_tol;}
+
      // interpolate the magnetic properties to B locations
      // magnetic properties are cell nodal
      // B locations are face centered
@@ -174,6 +178,17 @@ private:
      amrex::Real m_mag_alpha;
      /** gyromagnetic ratio, should be a negative value, only applies for magnetic materials */
      amrex::Real m_mag_gamma;
+
+     // If the magnitude of the magnetization deviates by more than this amount relative
+     // to the user-defined Ms, abort.  Default 0.1.
+     amrex::Real m_mag_normalized_error;
+
+     // maximum iteration count for the second-order time advancement scheme of M field, default 100
+     int m_mag_max_iter;
+
+     // the relative tolerance for the second-order time advancement scheme of M field, default 0.0001
+     amrex::Real m_mag_tol;
+
 #endif
 
      /** Multifab for m_sigma */

Source/FieldSolver/FiniteDifferenceSolver/MacroscopicProperties/MacroscopicProperties.cpp

@@ -73,6 +73,16 @@ MacroscopicProperties::ReadParameters ()
         m_mag_gamma_parser.reset(new ParserWrapper<3>(
                                   makeParser(m_str_mag_gamma_function,{"x","y","z"})));
     }
+
+    m_mag_normalized_error = 0.1;
+    pp.get("mag_normalized_error",m_mag_normalized_error);
+
+    m_mag_max_iter = 100;
+    pp.get("mag_max_iter",m_mag_max_iter);
+
+    m_mag_tol = 0.0001;
+    pp.get("mag_tol",m_mag_tol);
+
 #endif
 }