Add fixed-cell i-PI socket driver

Author: jianrui geng

docs/advanced/input_files/input-main.md

@@ -583,6 +583,7 @@
   - relax: perform structure relaxation calculations, the relax_nmax parameter depicts the maximal number of ionic iterations
   - cell-relax: perform cell relaxation calculations
   - md: perform molecular dynamics simulations
+  - socket: run as a socket client for external drivers using the i-PI protocol
   - get_pchg: obtain partial (band-decomposed) charge densities (for LCAO basis only). See out_pchg for more information
   - get_wf: obtain real space wave functions (for LCAO basis only). See out_wfc_norm and out_wfc_re_im for more information
   - get_s: obtain the overlap matrix formed by localized orbitals (for LCAO basis with multiple k points). the file name is SR.csr with file format being the same as that generated by out_mat_hs2
@@ -814,7 +815,12 @@
 ### chg_extrap
 
 - **Type**: String
-- **Description**: Charge extrapolation method for MD and relaxation calculations.
+- **Description**: Charge extrapolation method for MD, relaxation, and socket-driven calculations.
+
+  When set to default, ABACUS chooses second-order for md, first-order for
+  relax/cell-relax/socket, and atomic for other calculations. Socket-driven
+  molecular dynamics can explicitly set second-order if the external driver
+  updates structures smoothly enough for second-order extrapolation.
 - **Default**: default
 
 ### nb2d

docs/parameters.yaml

@@ -28,6 +28,7 @@ parameters:
       * relax: perform structure relaxation calculations, the relax_nmax parameter depicts the maximal number of ionic iterations
       * cell-relax: perform cell relaxation calculations
       * md: perform molecular dynamics simulations
+      * socket: run as a socket client for external drivers using the i-PI protocol
       * get_pchg: obtain partial (band-decomposed) charge densities (for LCAO basis only). See out_pchg for more information
       * get_wf: obtain real space wave functions (for LCAO basis only). See out_wfc_norm and out_wfc_re_im for more information
       * get_s: obtain the overlap matrix formed by localized orbitals (for LCAO basis with multiple k points). the file name is SR.csr with file format being the same as that generated by out_mat_hs2
@@ -314,7 +315,12 @@ parameters:
     category: System variables
     type: String
     description: |
-      Charge extrapolation method for MD and relaxation calculations.
+      Charge extrapolation method for MD, relaxation, and socket-driven calculations.
+
+      When set to default, ABACUS chooses second-order for md, first-order for
+      relax/cell-relax/socket, and atomic for other calculations. Socket-driven
+      molecular dynamics can explicitly set second-order if the external driver
+      updates structures smoothly enough for second-order extrapolation.
     default_value: default
     unit: ""
     availability: ""

source/CMakeLists.txt

@@ -477,7 +477,9 @@ add_library(
   driver
   OBJECT
   source_main/driver.cpp
-  source_main/driver_run.cpp)
+  source_main/driver_run.cpp
+  source_main/driver_ipi.cpp
+  source_main/ipi_socket.cpp)
 
 list(APPEND device_srcs
   source_pw/module_pwdft/kernels/nonlocal_op.cpp

source/source_io/module_parameter/read_input_item_system.cpp

@@ -75,7 +75,7 @@ void ReadInput::item_system()
     }
     {
         Input_Item item("calculation");
-        item.annotation = "scf; relax; md; cell-relax; nscf; get_s; get_wf; get_pchg; gen_bessel; gen_opt_abfs; test_memory; test_neighbour";
+        item.annotation = "scf; relax; md; socket; cell-relax; nscf; get_s; get_wf; get_pchg; gen_bessel; gen_opt_abfs; test_memory; test_neighbour";
         item.category = "System variables";
         item.type = "String";
         item.description = R"(Specify the type of calculation.
@@ -85,6 +85,7 @@ void ReadInput::item_system()
 * relax: perform structure relaxation calculations, the relax_nmax parameter depicts the maximal number of ionic iterations
 * cell-relax: perform cell relaxation calculations
 * md: perform molecular dynamics simulations
+* socket: run as a socket client for external drivers using the i-PI protocol
 * get_pchg: obtain partial (band-decomposed) charge densities (for LCAO basis only). See out_pchg for more information
 * get_wf: obtain real space wave functions (for LCAO basis only). See out_wfc_norm and out_wfc_re_im for more information
 * get_s: obtain the overlap matrix formed by localized orbitals (for LCAO basis with multiple k points). the file name is SR.csr with file format being the same as that generated by out_mat_hs2
@@ -102,6 +103,7 @@ void ReadInput::item_system()
             std::vector<std::string> callist = {"scf",
                                                 "relax",
                                                 "md",
+                                                "socket",
                                                 "cell-relax",
                                                 "nscf",
                                                 "get_s",
@@ -266,7 +268,7 @@ void ReadInput::item_system()
         item.description = "If set to True, calculate the force at the end of the electronic iteration.";
         item.default_value = "False";
         item.reset_value = [](const Input_Item& item, Parameter& para) {
-            std::vector<std::string> use_force = {"cell-relax", "relax", "md"};
+            std::vector<std::string> use_force = {"cell-relax", "relax", "md", "socket"};
             std::vector<std::string> not_use_force = {"get_wf", "get_pchg", "get_s"};
             if (std::find(use_force.begin(), use_force.end(), para.input.calculation) != use_force.end())
             {
@@ -873,7 +875,12 @@ Available options are:
         item.annotation = "atomic; first-order; second-order; dm:coefficients of SIA";
         item.category = "System variables";
         item.type = "String";
-        item.description = "Charge extrapolation method for MD and relaxation calculations.";
+        item.description = R"(Charge extrapolation method for MD, relaxation, and socket-driven calculations.
+
+When set to default, ABACUS chooses second-order for md, first-order for
+relax/cell-relax/socket, and atomic for other calculations. Socket-driven
+molecular dynamics can explicitly set second-order if the external driver
+updates structures smoothly enough for second-order extrapolation.)";
         item.default_value = "default";
         read_sync_string(input.chg_extrap);
         item.reset_value = [](const Input_Item& item, Parameter& para) {
@@ -882,7 +889,7 @@ Available options are:
                 para.input.chg_extrap = "second-order";
             }
             else if (para.input.chg_extrap == "default"
-                     && (para.input.calculation == "relax" || para.input.calculation == "cell-relax"))
+                     && (para.input.calculation == "relax" || para.input.calculation == "cell-relax" || para.input.calculation == "socket"))
             {
                 para.input.chg_extrap = "first-order";
             }

source/source_io/test_serial/read_input_item_test.cpp

@@ -362,6 +362,11 @@ TEST_F(InputTest, Item_test)
         it->second.reset_value(it->second, param);
         EXPECT_EQ(param.input.chg_extrap, "first-order");
 
+        param.input.chg_extrap = "default";
+        param.input.calculation = "socket";
+        it->second.reset_value(it->second, param);
+        EXPECT_EQ(param.input.chg_extrap, "first-order");
+
         param.input.chg_extrap = "default";
         param.input.calculation = "none";
         it->second.reset_value(it->second, param);

source/source_main/driver.h

@@ -36,6 +36,7 @@ class Driver
 
     // the actual calculations
     void driver_run();
+    void driver_ipi_run();
 
     // Init harewares according to Input parameters
     void init_hardware();