cmake: support LAMMPS in built-in mode; remove kspace requirement

doc/install/install-lammps.md

@@ -17,7 +17,13 @@ cd /some/workspace
 wget https://github.com/lammps/lammps/archive/stable_2Aug2023_update1.tar.gz
 tar xf stable_2Aug2023_update1.tar.gz
 ```
-The source code of LAMMPS is stored in the directory `lammps-stable_2Aug2023_update1`. Now go into the LAMMPS code and copy the DeePMD-kit module like this
+The source code of LAMMPS is stored in the directory `lammps-stable_2Aug2023_update1`.
+
+Then, you can [build LAMMPS](https://docs.lammps.org/Build.html) with either make or CMake.
+
+### With make
+
+Now go into the LAMMPS code and copy the DeePMD-kit module like this
 ```bash
 cd lammps-stable_2Aug2023_update1/src/
 cp -r $deepmd_source_dir/source/build/USER-DEEPMD .
@@ -40,6 +46,35 @@ The DeePMD-kit module can be removed from the LAMMPS source code by
 make no-user-deepmd
 ```
 
+### With CMake
+
+Now go into the LAMMPS directory and create a directory called `build`:
+
+```bash
+mkdir -p lammps-stable_2Aug2023_update1/build/
+cd lammps-stable_2Aug2023_update1/build/
+```
+
+Patch the LAMMPS `CMakeLists.txt` file:
+
+```bash
+echo "include(${deepmd_source_dir}/source/lmp/builtin.cmake)" >> ../cmake/CMakeLists.txt
+```
+
+It's expected to see one extra line in the end of `CMakeLists.txt`.
+
+Now build LAMMPS. You can install any other package you want.
+```bash
+cmake -D LAMMPS_INSTALL_RPATH=ON -D BUILD_SHARED_LIBS=yes -D CMAKE_INSTALL_PREFIX=${deepmd_root} -DCMAKE_PREFIX_PATH=${deepmd_root} ../cmake
+make -j4
+make install
+```
+
+If everything works fine, you will end up with an executable `${deepmd_root}/bin/lmp`.
+```bash
+${deepmd_root}/bin/lmp -h
+```
+
 ## Install LAMMPS (plugin mode)
 Starting from `8Apr2021`, LAMMPS also provides a plugin mode, allowing one to build LAMMPS and a plugin separately.
 
@@ -56,9 +91,9 @@ The source code of LAMMPS is stored in the directory `lammps-stable_2Aug2023_upd
 mkdir -p lammps-stable_2Aug2023_update1/build/
 cd lammps-stable_2Aug2023_update1/build/
 ```
-Now build LAMMPS. Note that `PLUGIN` and `KSPACE` packages must be enabled, and `BUILD_SHARED_LIBS` must be set to `yes`. You can install any other package you want.
+Now build LAMMPS. Note that `PLUGIN` must be enabled, and `BUILD_SHARED_LIBS` must be set to `yes`. You can install any other package you want.
 ```bash
-cmake -D PKG_PLUGIN=ON -D PKG_KSPACE=ON -D LAMMPS_INSTALL_RPATH=ON -D BUILD_SHARED_LIBS=yes -D CMAKE_INSTALL_PREFIX=${deepmd_root} -D CMAKE_INSTALL_LIBDIR=lib -D CMAKE_INSTALL_FULL_LIBDIR=${deepmd_root}/lib ../cmake
+cmake -D PKG_PLUGIN=ON -D LAMMPS_INSTALL_RPATH=ON -D BUILD_SHARED_LIBS=yes -D CMAKE_INSTALL_PREFIX=${deepmd_root} -D CMAKE_INSTALL_LIBDIR=lib -D CMAKE_INSTALL_FULL_LIBDIR=${deepmd_root}/lib ../cmake
 make -j4
 make install
 ```

source/install/build_lammps.sh

@@ -23,7 +23,7 @@ fi
 cd ${BUILD_TMP_DIR}/lammps-${LAMMPS_VERSION}
 mkdir -p ${BUILD_TMP_DIR}/lammps-${LAMMPS_VERSION}/build
 cd ${BUILD_TMP_DIR}/lammps-${LAMMPS_VERSION}/build
-cmake -C ../cmake/presets/all_off.cmake -D PKG_PLUGIN=ON -D PKG_KSPACE=ON -D PKG_MOLECULE=ON -DLAMMPS_EXCEPTIONS=yes -D BUILD_SHARED_LIBS=yes -D LAMMPS_INSTALL_RPATH=ON -D CMAKE_INSTALL_PREFIX=${INSTALL_PREFIX} -D CMAKE_INSTALL_LIBDIR=lib -D CMAKE_INSTALL_FULL_LIBDIR=${INSTALL_PREFIX}/lib ../cmake
+cmake -C ../cmake/presets/all_off.cmake -D PKG_PLUGIN=ON -D PKG_MOLECULE=ON -DLAMMPS_EXCEPTIONS=yes -D BUILD_SHARED_LIBS=yes -D LAMMPS_INSTALL_RPATH=ON -D CMAKE_INSTALL_PREFIX=${INSTALL_PREFIX} -D CMAKE_INSTALL_LIBDIR=lib -D CMAKE_INSTALL_FULL_LIBDIR=${INSTALL_PREFIX}/lib ../cmake
 
 make -j${NPROC}
 make install

source/lmp/builtin.cmake

@@ -0,0 +1,31 @@
+# This file should be included in the end of
+# ${LAMMPS_SOURCE_DIR}/cmake/CMakeLists.txt
+# include(/path/to/deepmd_source/source/lmp/builtin.cmake)
+
+# assume LAMMPS CMake file has been executed, so these target/variables exist:
+# lammps LAMMPS_SOURCE_DIR get_lammps_version
+
+get_lammps_version(${LAMMPS_SOURCE_DIR}/version.h LAMMPS_VERSION_NUMBER)
+
+configure_file("${CMAKE_CURRENT_LIST_DIR}/deepmd_version.h.in"
+               "${CMAKE_CURRENT_BINARY_DIR}/deepmd_version.h" @ONLY)
+
+file(GLOB DEEPMD_LMP_SRC ${CMAKE_CURRENT_LIST_DIR}/*.cpp)
+
+find_package(DeePMD REQUIRED)
+target_sources(
+  lammps
+  PRIVATE ${DEEPMD_LMP_SRC}
+          ${LAMMPS_SOURCE_DIR}/KSPACE/pppm.cpp # for pppm_dplr
+          ${LAMMPS_SOURCE_DIR}/KSPACE/fft3d.cpp
+          ${LAMMPS_SOURCE_DIR}/KSPACE/fft3d_wrap.cpp
+          ${LAMMPS_SOURCE_DIR}/KSPACE/remap.cpp
+          ${LAMMPS_SOURCE_DIR}/KSPACE/remap_wrap.cpp
+          ${LAMMPS_SOURCE_DIR}/EXTRA-FIX/fix_ttm.cpp # for ttm
+)
+target_link_libraries(lammps PUBLIC DeePMD::deepmd_c)
+target_include_directories(
+  lammps PRIVATE ${CMAKE_CURRENT_BINARY_DIR} ${CMAKE_CURRENT_LIST_DIR}
+                 ${LAMMPS_SOURCE_DIR}/KSPACE ${LAMMPS_SOURCE_DIR}/EXTRA-FIX)
+target_compile_definitions(
+  lammps PRIVATE "LAMMPS_VERSION_NUMBER=${LAMMPS_VERSION_NUMBER}")

source/lmp/plugin/CMakeLists.txt

@@ -49,9 +49,16 @@ if(DEFINED LAMMPS_SOURCE_ROOT OR DEFINED LAMMPS_VERSION)
   configure_file("../deepmd_version.h.in"
                  "${CMAKE_CURRENT_BINARY_DIR}/deepmd_version.h" @ONLY)
 
-  file(GLOB LMP_SRC deepmdplugin.cpp ../*.cpp
-       ${LAMMPS_SOURCE_ROOT}/src/kspace.cpp # for pppm_dplr
-       ${LAMMPS_SOURCE_ROOT}/src/KSPACE/pppm.cpp)
+  file(
+    GLOB
+    LMP_SRC
+    deepmdplugin.cpp
+    ../*.cpp
+    ${LAMMPS_SOURCE_ROOT}/src/KSPACE/pppm.cpp # for pppm_dplr
+    ${LAMMPS_SOURCE_ROOT}/src/KSPACE/fft3d.cpp
+    ${LAMMPS_SOURCE_ROOT}/src/KSPACE/fft3d_wrap.cpp
+    ${LAMMPS_SOURCE_ROOT}/src/KSPACE/remap.cpp
+    ${LAMMPS_SOURCE_ROOT}/src/KSPACE/remap_wrap.cpp)
   if(LAMMPS_VERSION_NUMBER GREATER 20210831)
     list(APPEND LMP_SRC ${LAMMPS_SOURCE_ROOT}/src/EXTRA-FIX/fix_ttm.cpp
     )# for ttm