more refactoring of MDI engine

src/MDI/fix_mdi_aimd.cpp

@@ -206,14 +206,14 @@ void FixMDIAimd::post_force(int vflag)
     f[i][2] += buf3[3*ilocal+2] * mdi2lmp_force;
   }
 
-  // optionally request energy from MDI engine
+  // optionally request potential energy from MDI engine
   // divide by nprocs so each proc stores a portion
 
   if (eflag_global) {
-    ierr = MDI_Send_command("<ENERGY",mdicomm);
-    if (ierr) error->all(FLERR,"MDI: <ENERGY command");
+    ierr = MDI_Send_command("<PE",mdicomm);
+    if (ierr) error->all(FLERR,"MDI: <PE command");
     ierr = MDI_Recv(&engine_energy,1,MDI_DOUBLE,mdicomm);
-    if (ierr) error->all(FLERR,"MDI: <ENERGY data");
+    if (ierr) error->all(FLERR,"MDI: <PE data");
     MPI_Bcast(&engine_energy,1,MPI_DOUBLE,0,world);
     engine_energy *= mdi2lmp_energy / nprocs;
   }

src/MDI/fix_mdi_engine.cpp

@@ -49,6 +49,8 @@ int FixMDIEngine::setmask()
 
 void FixMDIEngine::setup(int vflag)
 {
+  // engine is now at FORCES node
+
   mdi_engine->engine_node("@FORCES");
 }
 
@@ -56,6 +58,8 @@ void FixMDIEngine::setup(int vflag)
 
 void FixMDIEngine::post_integrate()
 {
+  // engine is now at COORDS node for MD
+
   mdi_engine->engine_node("@COORDS");
 }
 
@@ -63,6 +67,8 @@ void FixMDIEngine::post_integrate()
 
 void FixMDIEngine::min_pre_force(int vflag)
 {
+  // engine is now at COORDS node for minimizer
+
   mdi_engine->engine_node("@COORDS");
 }
 
@@ -70,6 +76,8 @@ void FixMDIEngine::min_pre_force(int vflag)
 
 void FixMDIEngine::post_force(int vflag)
 {
+  // engine is now at FORCES node for MD
+
   mdi_engine->engine_node("@FORCES");
 }
 
@@ -77,6 +85,8 @@ void FixMDIEngine::post_force(int vflag)
 
 void FixMDIEngine::min_post_force(int vflag)
 {
+  // engine is now at FORCES node for minimizer
+
   mdi_engine->engine_node("@FORCES");
 }
 
@@ -84,5 +94,7 @@ void FixMDIEngine::min_post_force(int vflag)
 
 void FixMDIEngine::end_of_step()
 {
+  // engine is now at ENDSTEP node for MD
+
   mdi_engine->engine_node("@ENDSTEP");
 }

src/MDI/library_mdi.cpp

@@ -98,7 +98,14 @@ int MDI_Plugin_init_lammps()
     lmp = lammps_open(mdi_argc, mdi_argv, mpi_world_comm, nullptr);
   else
     lmp = lammps_open_no_mpi(mdi_argc, mdi_argv, nullptr);
+
+  // process the specified input script
+  // must contain "mdi engine" command
+
   lammps_file(lmp, filename);
+
+  // shut down the plugin
+
   lammps_close(lmp);
 
   return 0;

src/MDI/mdi_engine.h

@@ -35,8 +35,10 @@ class MDIEngine : public Command {
   void engine_node(const char *node);
 
  private:
-  int lmpunits;    // REAL or METAL or NATIVE
-  int root;        // 1 for proc 0, otherwise 0
+  int lmpunits;      // REAL or METAL or NATIVE
+  int root;          // 1 for proc 0, otherwise 0
+
+  int enable_fix;    // 1 if mdi engine command asked for node support
 
   // state of MDI engine
 
@@ -59,8 +61,16 @@ class MDIEngine : public Command {
 
   int nbytes;         // NBYTES command value used by other commands
 
+  // @INIT_SYS state
+
+  int sys_natoms;
+  int *sys_types;
+  double *sys_charges,*sys_coords,*sys_velocities;
+  double *sys_cell,*sys_cell_displ;
+    
   // create_atoms state
 
+
   int create_atoms_flag;
   int create_natoms;
   tagint *create_id;
@@ -91,29 +101,52 @@ class MDIEngine : public Command {
   void mdi_commands();
   void mdi_md();
   void mdi_optg();
+  void mdi_sys();
 
   void evaluate();
 
+  void receive_cell();
+  void receive_cell_default();
+  void receive_cell_sys();
+
+  void receive_cell_displ();
+  void receive_cell_displ_default();
+  void receive_cell_displ_sys();
+
+  void receive_charges();
+  void receive_charges_sys();
+
+  void receive_coords();
+  void receive_coords_sys();
+
   void receive_natoms();
-  void send_natoms();
-  void send_ntypes();
+  void receive_natoms_default();
+  void receive_natoms_sys();
+
+  void receive_types();
+  void receive_types_sys();
+
+  void receive_velocities();
+  void receive_velocities_sys();
 
   void receive_double1(int);
   void receive_int1(int);
   void receive_double3(int, int);
+
+  void send_natoms();
+  void send_ntypes();
+
   void send_double1(int);
   void send_int1(int);
   void send_double3(int);
   void send_labels();
 
   void send_total_energy();
-  void send_energy();
+  void send_pe();
   void send_ke();
 
   void send_cell();
-  void receive_cell();
-  void send_celldispl();
-  void receive_celldispl();
+  void send_cell_displ();
 
   void nbytes_command();
   void single_command();