fix: get_pchg_lcao.cpp with c^* c^T

[Fisherd99]

Fix a bug in get_pchg_lcao.cpp

Since psiMulPsiMpi uses a plain transpose, the conjugate must be handled explicitly to form C^* C^T.

Same treatment can be seen source/elecstate/module_dm/cal_dm_psi.cpp:107-110. I think current code in get_pchg_lcao.cpp is missed.

[Fisherd99]

Unit Test of "get_pchg_k" fails because I haven't modified the reference file. I think we should first discuss whether the formula is correct, then decide whether to modify the reference file.

[AsTonyshment]

Thanks for catching and fixing this issue! I originally added the LCAO multi-k partial-charge path in PR #4698 a couple of years ago (when this file was still named istate_charge.cpp); before that, the implementation only supported the Gamma point and used real-valued psi::Psi<double>, for which complex conjugation makes no difference. When extending it to the complex-valued multi-k path, I overlooked that psiMulPsiMpi uses a plain transpose and therefore requires explicit conjugation to form C^* W C^T. Your fix is correct.

Please also update tests/03_NAO_multik/get_pchg/result.ref and tests/03_NAO_multik/get_pchg_k/result.ref with the corrected results. After that, this looks good to me :)

[Fisherd99]

OK. I've updated the two reference files. Furthermore, I think LTS branch should also need this fix.

[mohanchen]

You can also propose a PR to LTS