feat(relax): output final CIF structure after relaxation (#7452)

Add CIF file output for the final relaxed structure.
Fixes #7451

Author: mintleaf84

source/source_relax/relax_driver.cpp

@@ -172,6 +172,14 @@ void Relax_Driver::relax_driver(
         ++istep;
     } // end while (istep <= inp.relax_nmax && !stop)
 
+    // output the final relaxed structure in CIF format
+    if (inp.calculation == "relax" || inp.calculation == "cell-relax")
+    {
+        ModuleIO::CifParser::write(PARAM.globalv.global_out_dir + "STRU_FINAL.cif",
+                                   ucell,
+                                   "# Generated by ABACUS ModuleIO::CifParser",
+                                   "data_?");
+    }
 
 	if (inp.calculation == "relax" || inp.calculation == "cell-relax")
 	{