Refactor: move EXX file-list broadcast out of source_cell (#7635) (#7663)

bcast_cell.cpp reached into GlobalC::exx_info (source_hamilt/module_xc) to
broadcast the ABFS/JLE orbital-file lists, making the source_cell
data-structure layer depend on a higher layer.

The ABFS/JLE orbital files are an LCAO-only concept, so the broadcast is
placed in the LCAO EXX manager: add bcast_exx_file_lists() in
source_lcao/setup_exx.{h,cpp} and invoke it at the start of Exx_NAO::init(),
before Exx_LRI copies info_ri. init() runs in ESolver_KS_LCAO::before_all_runners
(reused by TDDFT/DM2rho/DoubleXC; LR reuses the moved Exx_LRI), on all ranks,
after setup_cell has populated the lists on rank 0 and before every consumer
(RI-EXX, opt-ABFs generate_matrix, RPA postSCF).

This removes the exx_info.h include, the helper, and the three broadcast
calls from bcast_cell.cpp. The per-ionic-step re-broadcast previously done
via bcast_unitcell is dropped, which is behaviour-neutral: the file lists
are static once read from STRU.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: Critsium-xy

source/source_cell/bcast_cell.cpp

@@ -1,30 +1,11 @@
 #include "unitcell.h"
 #include "source_base/parallel_common.h"
 
-#include "source_hamilt/module_xc/exx_info.h" // use GlobalC::exx_info
-
 #include <string>
 #include <vector>
 
 namespace unitcell
 {
-#if defined(__MPI) && defined(__EXX)
-    // Broadcast a vector<string> from rank 0 to all ranks.
-    // Replaces the former cereal-based ModuleBase::bcast_data_cereal, which
-    // was only ever used here to broadcast plain lists of ABFS file names and
-    // pulled source_cell into a dependency on source_lcao/module_ri.
-    static void bcast_string_vector(std::vector<std::string>& v)
-    {
-        int size = static_cast<int>(v.size());
-        Parallel_Common::bcast_int(size);
-        v.resize(size);
-        for (int i = 0; i < size; ++i)
-        {
-            Parallel_Common::bcast_string(v[i]);
-        }
-    }
-#endif
-
     void bcast_atoms_tau(Atom* atoms,
                          const int ntype)
     {
@@ -131,12 +112,6 @@ namespace unitcell
         {
             Parallel_Common::bcast_string(ucell.orbital_fn[i]);
         }
-
-        #ifdef __EXX
-        bcast_string_vector(GlobalC::exx_info.info_ri.files_abfs);
-        bcast_string_vector(GlobalC::exx_info.info_opt_abfs.files_abfs);
-        bcast_string_vector(GlobalC::exx_info.info_opt_abfs.files_jles);
-        #endif
         return;
     #endif
     }

source/source_lcao/setup_exx.cpp

@@ -2,6 +2,42 @@
 
 #ifdef __EXX
 #include "source_lcao/module_ri/Exx_LRI_interface.h"
+#include "source_hamilt/module_xc/exx_info.h" // use the global Exx_Info
+#if defined(__MPI)
+#include "source_base/parallel_common.h"
+#include <string>
+#include <vector>
+#endif
+#endif
+
+#ifdef __EXX
+#if defined(__MPI)
+namespace
+{
+    // Broadcast a vector<string> from rank 0 to all ranks.
+    // Moved here from source_cell/bcast_cell.cpp so that source_cell no longer
+    // depends on the XC module just to distribute these ABFS file-name lists.
+    void bcast_string_vector(std::vector<std::string>& v)
+    {
+        int size = static_cast<int>(v.size());
+        Parallel_Common::bcast_int(size);
+        v.resize(size);
+        for (int i = 0; i < size; ++i)
+        {
+            Parallel_Common::bcast_string(v[i]);
+        }
+    }
+} // namespace
+#endif
+
+void bcast_exx_file_lists()
+{
+#if defined(__MPI)
+    bcast_string_vector(GlobalC::exx_info.info_ri.files_abfs);
+    bcast_string_vector(GlobalC::exx_info.info_opt_abfs.files_abfs);
+    bcast_string_vector(GlobalC::exx_info.info_opt_abfs.files_jles);
+#endif
+}
 #endif
 
 template <typename TK>
@@ -20,6 +56,11 @@ void Exx_NAO<TK>::init()
     //  which cause the failure of the subsequent procedure reused by ESolver_LCAO_TDDFT
     // 2. always construct but only initialize when if(cal_exx) is true
     //  because some members like two_level_step are used outside if(cal_exx)
+
+    // Distribute the ABFS/JLE file lists (read from STRU on rank 0) to all ranks
+    // before Exx_LRI copies info_ri below.
+    bcast_exx_file_lists();
+
     if (GlobalC::exx_info.info_ri.real_number)
     {
         this->exd = std::make_shared<Exx_LRI_Interface<TK, double>>(GlobalC::exx_info.info_ri, GlobalC::exx_info.info_global);

source/source_lcao/setup_exx.h

@@ -47,5 +47,18 @@ class Exx_NAO
 
 };
 
+#ifdef __EXX
+/**
+ * @brief Broadcast the ABFS/JLE orbital-file lists held in the global Exx_Info instance.
+ *
+ * The lists are read from STRU on rank 0 during setup_cell and must be
+ * distributed to all ranks before the LCAO EXX/RI module consumes them.
+ * This logic lives here (rather than in source_cell or the generic XC module)
+ * because the ABFS/JLE orbital files are an LCAO-only concept. It is invoked at
+ * the start of Exx_NAO::init(), before Exx_LRI copies info_ri.
+ */
+void bcast_exx_file_lists();
+#endif
+
 
 #endif