[lanshuyue]

Summary

• Append sorted DFT+U occupation-matrix eigenvalues to the latest occ_mat.txt when out_occ_mat is enabled.
• Keep the compact occupation matrices and numbered occ_matg*.txt snapshots unchanged. Eigenvalues are comment lines, so occ_mat.txt remains valid restart input.
• For collinear calculations, diagonalize each spin block with the existing Jacobi helper; for SOC, reconstruct the complex spinor matrix and use LAPACK zheev.

Example:

# eigenvalues atom 1 L 2 spin 1: 0.70000000 0.80000000 0.80000000 0.80000000 0.90000000
# eigenvalues atom 1 L 2 spin 2: 0.20000000 0.20000000 0.20000000 0.20000000 0.20000000

Verification

• cmake --build build --target MODULE_PW_dftu_base_test -j4 — passed.
• OMP_NUM_THREADS=1 ./build/source/source_pw/module_pwdft/unittests/MODULE_PW_dftu_base_test --gtest_brief=1 — 29/29 passed in a normal MPI runtime environment.
• git diff --check — passed.
• python3 tools/03_code_analysis/agent_governance_check.py --staged — documentation-sync advisory only.

Documentation

No new INPUT parameter or parsing behavior. The output lines are self-describing, and out_occ_mat already documents the file. The format is described here for review.