Growl1234 · Oct 25, 2026 · Oct 31, 2026
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
@@ -80,41 +80,10 @@ jobs:
         run: |
           cd toolchain
           ./install_abacus_toolchain_new.sh --with-dftd4=install --dry-run -j8
+          ./scripts/stage3/install_libxc.sh
           ./scripts/stage4/install_stage4.sh
           cd ..
 
-      # Keep the image's LibXC version: only enable the KXC needed by LR gradients.
-      - name: Identify LibXC version
-        id: libxc
-        run: echo "version=$(pkg-config --modversion libxc)" >> "${GITHUB_OUTPUT}"
-
-      - name: Cache LibXC with KXC
-        id: libxc-cache
-        uses: actions/cache@v6
-        with:
-          path: toolchain/install/libxc-kxc
-          key: libxc-kxc-v1-${{ runner.os }}-${{ runner.arch }}-${{ steps.compiler.outputs.fingerprint }}-${{ steps.libxc.outputs.version }}
-
-      - name: Build LibXC with KXC
-        if: steps.libxc-cache.outputs.cache-hit != 'true'
-        env:
-          LIBXC_VERSION: ${{ steps.libxc.outputs.version }}
-        run: |
-          wget -q "https://gitlab.com/libxc/libxc/-/archive/${LIBXC_VERSION}/libxc-${LIBXC_VERSION}.tar.gz" -O /tmp/libxc-kxc.tar.gz
-          mkdir -p /tmp/libxc-kxc-source
-          tar -xzf /tmp/libxc-kxc.tar.gz --strip-components=1 -C /tmp/libxc-kxc-source
-          cmake -S /tmp/libxc-kxc-source -B /tmp/libxc-kxc-build -G Ninja \
-            -DCMAKE_BUILD_TYPE=Release \
-            -DCMAKE_INSTALL_PREFIX="${GITHUB_WORKSPACE}/toolchain/install/libxc-kxc" \
-            -DCMAKE_INSTALL_LIBDIR=lib \
-            -DBUILD_SHARED_LIBS=ON -DENABLE_FORTRAN=OFF -DBUILD_TESTING=OFF \
-            -DDISABLE_KXC=OFF -DDISABLE_LXC=ON
-          cmake --build /tmp/libxc-kxc-build -j8
-          cmake --install /tmp/libxc-kxc-build
-
-      - name: Use KXC-enabled LibXC at runtime
-        run: echo "LD_LIBRARY_PATH=${GITHUB_WORKSPACE}/toolchain/install/libxc-kxc/lib:${LD_LIBRARY_PATH:-}" >> "${GITHUB_ENV}"
-
       - name: Test LR excited-state tracking checker
         run: python3 tests/integrate/validation_tools/test_es_check.py
 
@@ -126,7 +95,6 @@ jobs:
             -DCMAKE_EXPORT_COMPILE_COMMANDS=ON \
             -DENABLE_MLALGO=ON \
             -DENABLE_LIBXC=ON \
-            -DLibxc_DIR="${GITHUB_WORKSPACE}/toolchain/install/libxc-kxc/share/cmake/Libxc" \
             -DENABLE_LIBRI=ON \
             -DENABLE_GOOGLEBENCH=OFF \
             -DENABLE_JSON=ON \

diff --git a/toolchain/README.md b/toolchain/README.md
@@ -203,7 +203,7 @@ Mix online and offline packages as needed - the toolchain automatically detects
 | ScaLAPACK | 2.2.3 / 2.2.1 | Parallel linear algebra | BSD-3-Clause | Install |
 | **Scientific Libraries** |||||
 | FFTW | 3.3.11 / 3.3.10 | Fast Fourier Transform | GPL-2.0-or-later | Install |
-| LibXC | 7.0.0 / 6.2.2 | Exchange-correlation | MPL-2.0 | Install |
+| LibXC | 7.1.2 / 7.0.0 | Exchange-correlation | MPL-2.0 | Install |
 | ELPA | 2026.02.001 / 2024.05.001 | Eigenvalue solver | LGPL-3.0-only | Install |
 | **Advanced Features** |||||
 | Cereal | pinned commit | C++ Serialization | BSD | Install |
@@ -247,14 +247,41 @@ CMAKE_VERSION="main"        # main=3.31.7, alt=3.30.5
 OPENMPI_VERSION="main"      # main=5.0.10, alt=4.1.8
 OPENBLAS_VERSION="main"     # main=0.3.33, alt=0.3.30
 ELPA_VERSION="main"         # main=2026.02.001, alt=2024.05.001
-LIBXC_VERSION="main"        # main=7.0.0, alt=6.2.2
+LIBXC_VERSION="main"        # main=7.1.2, alt=7.0.0
 SCALAPACK_VERSION="main"    # main=2.2.3, alt=2.2.1
 # Optional Libraries
 LIBTORCH_VERSION="main"     # main=2.1.2, alt=1.12.1 (use alt for older GLIBC)
 ```
 
 and other `toolchain_*.sh` scripts share the same version selection.
 
+#### LibXC KXC and HSE excited-state forces
+
+The default LibXC `main` version is 7.1.2; `alt` selects 7.0.0.
+The installer enables third derivatives (KXC) with `-DMAXORDER=3` for
+LibXC 7.1 and newer, or `-DDISABLE_KXC=OFF -DDISABLE_LXC=ON` for older
+versions. These settings apply when the toolchain builds LibXC, not when
+using a system or externally installed library.
+
+Starting with LibXC 7.1.0, the standard omega-PBEH (WPBEH) functional and
+its HSE03/HSE06 combinations provide derivatives only through second order
+(FXC). Enabling KXC at build time does not restore KXC for those functionals.
+Upstream restricted their derivative order because of insufficient smoothness
+at piecewise junctions and numerical stability issues; see the
+[upstream change](https://gitlab.com/libxc/libxc/-/commit/df265b822368651dce578707bd5753d015480feb).
+This limitation concerns HSE LR-TDDFT analytical excited-state forces;
+it does not by itself prevent ground-state HSE calculations or spectra
+requiring only FXC.
+
+Users requiring the existing HSE LR-TDDFT force path can select the older
+version when installing dependencies:
+
+```bash
+cd toolchain
+./toolchain_gnu.sh --package-version libxc:alt
+source install/setup
+```
+
 #### Global Version Strategy
 
 - **Default Behavior**: All packages use their **main** versions unless explicitly overridden

diff --git a/toolchain/scripts/stage3/install_libxc.sh b/toolchain/scripts/stage3/install_libxc.sh
@@ -63,15 +63,23 @@ case "$with_libxc" in
             cd libxc-${libxc_ver}
             mkdir build 
             cd build
+            # LibXC 7.1 replaced the per-order switches with MAXORDER.
+            IFS=. read -r libxc_major libxc_minor libxc_patch <<< "${libxc_ver}"
+            if (( libxc_major > 7 || (libxc_major == 7 && libxc_minor >= 1) )); then
+                libxc_derivative_args=(-DMAXORDER=3)
+            else
+                libxc_derivative_args=(-DDISABLE_KXC=OFF -DDISABLE_LXC=ON)
+            fi
             cmake \
                 -DCMAKE_BUILD_TYPE=Release \
                 -DCMAKE_INSTALL_PREFIX=${pkg_install_dir} \
-                -DBUILD_SHARED_LIBS=ON \
+                -DBUILD_SHARED_LIBS=OFF \
                 -DCMAKE_INSTALL_LIBDIR=lib \
                 -DCMAKE_VERBOSE_MAKEFILE=ON \
                 -DENABLE_FORTRAN=ON \
                 -DENABLE_PYTHON=OFF \
-                -DBUILD_TESTING=OFF .. \
+                -DBUILD_TESTING=OFF \
+                "${libxc_derivative_args[@]}" .. \
                 > configure.log 2>&1 || tail -n ${LOG_LINES} configure.log
             make -j $(get_nprocs) > make.log 2>&1 || tail -n ${LOG_LINES} make.log
             make install > install.log 2>&1 || tail -n ${LOG_LINES} install.log