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abacusmodeling / abacus-develop

An electronic structure package based on either plane wave basis or numerical atomic orbitals.
GNU Lesser General Public License v3.0
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The ground-state energy decreases after structural relaxation #156

Closed lzcun closed 2 years ago

lzcun commented 2 years ago

I recently did 100 fs AIMD at 400K and optimized the geometry. I found the ground-state energy decreases after structural relaxation. The following is the FINAL_ETOT obtained calculating the SCF before and after the relaxation: The SCF before relaxing: image

The SCF after relaxing: image

I wonder whether it is a bug of ABACUS. And the basis_type all I used is 'lcao'.

YuLiu98 commented 2 years ago

Hi, can you provide related input and output files?

lzcun commented 2 years ago

OK, it has INPUT, STRU, and runing_scf.log about before and after relaxation. In doc 'relax' are the INPUT and output files.

relax_scf.zip

YuLiu98 commented 2 years ago

The width of Gaussian smearing is 0.2 Ry in the structural relaxation, while that is 0.02 Ry in the SCF, which causes the opposite results.

In the structural relaxation, the initial energy is -12644.7096725 eV, and the final energy is -12649.07110999118 eV. In the SCF, the initial energy is -12634.6964808355114656 eV, and the final energy is -12630.7770245020055881 eV.

And I notice that the max force of the relaxed STRU is > 0.01 eV/A if smearing_sigma = 0.02 Ry, showing that the parameters between relax and scf must be consistent to obtain the correct result.

lzcun commented 2 years ago

Thanks for your reply! Sorry, I did not notice that before. Now the results are right when the parameters become consistent.