Open lanshuyue opened 5 months ago
Noted. However I have some suggestions on your calculation setting and procedures. Does the following description match what you want to calculate?
@maki49 Hello, Do you have time to look at this issue?
The cause of this problem is: if in relaxation some atoms are fixed, the symmetry cannot be kept, but in ABACUS's relax procedure symmetry is analyzed only before the 1st ion step, so from the 2nd ion step the original higher symmetry is applied to the symmetrization of charge/force/stress of the current structure with lower symmetry.
@dyzheng To fix it, I will try to study and implement VASP's feature of "Analysis of constrained symmetry for selective dynamics", but it takes time. @lanshuyue You can continue your jobs with symmetry=0.
@kirk0830 yes, i think it's quite similar.
@kirk0830 yes, i think it's quite similar.
@lanshuyue if so, I think I would suggest you should relax both side of slab, increasing the thickness of slab or say number of atomic layers, calculate surface energy till you find there is a tendency approaching a converged value, I think this way might be more appropriate. Please note if you only relax one side, then the other side surface energy will be impossible to evaluate, it is the reason why I suggest relax both side concurrently.
HTH.
@kirk0830 yes, i think it's quite similar.
@lanshuyue if so, I think I would suggest you should relax both side of slab, increasing the thickness of slab or say number of atomic layers, calculate surface energy till you find there is a tendency approaching a converged value, I think this way might be more appropriate. Please note if you only relax one side, then the other side surface energy will be impossible to evaluate, it is the reason why I suggest relax both side concurrently.
HTH.
@kirk0830 Thank you for your suggestions!! I totally get that it's a common approach for calculating surface energies. However, my ultimate goal is to calculate adsorption energies, calculating surface energies being just one step. An asymmetric slab model aligns better with the system i'm analyzing. Plus, i'm currently replicating results from a research paper using this particular surface structure.
Thank you sooooo much for your advice and assistance!🤠
Describe the bug
When calculating the surface energy of a 7-layer bcc Mo, relaxation calculations were performed. In this process, the bottom three layers were held fixed to replicate a semi-infinite metal crystal, while the top four layers were allowed to relax.
When the symmetry setting was defaulted to 1, the calculation encountered issues as the structure optimization failed to converge. After each relaxation step, the LARGEST GRAD gradually increased, reaching up to 800 eV/Å.
In
running_relax.log
, it was noted that with each relaxation step, the atomic forces progressively increased. It was further observed that the forces acting on the fixed atoms and free atoms were symmetrical, which appeared to be the root cause of the abnormal behavior during the relaxation calculation process.Upon changing the symmetry setting to 0, the structure optimization proceeded as expected.
Expected behavior
No response
To Reproduce
NUMERICAL_ORBITAL Mo_gga_7au_100Ry_4s2p2d1f.orb
LATTICE_CONSTANT 1.8897261258369282
LATTICE_VECTORS 28.519325000 0.0000000000 0.0000000000 0.0000000000 2.2532210000 -1.593268000 0.0000000000 2.2532210000 1.5932680000
ATOMIC_POSITIONS Direct
Mo 0.0000000000 7 0.2629800000 0.0000000000 0.0000000000 0 0 0 mag 0.0 0.3419860000 0.5000000000 0.5000000000 0 0 0 mag 0.0 0.4209930000 0.0000000000 0.0000000000 0 0 0 mag 0.0 0.5000000000 0.5000000000 0.5000000000 1 1 1 mag 0.0 0.5790070000 0.0000000000 0.0000000000 1 1 1 mag 0.0 0.6580140000 0.5000000000 0.5000000000 1 1 1 mag 0.0 0.7370200000 0.0000000000 0.0000000000 1 1 1 mag 0.0
INPUT_PARAMETERS
Parameters (1.General)
suffix Moslab15_fix6 calculation relax ntype 1 nbands 52
symmetry 0
pseudo_dir ./ cal_stress 1
Parameters (2.Iteration)
ecutwfc 100 scf_nmax 100 relax_nmax 100
Parameters (3.Basis)
basis_type lcao
Parameters (4.Smearing)
smearing_method mp smearing_sigma 0.0036
Parameters (5.Mixing)
mixing_type broyden mixing_beta 0.4
K_POINTS 0 Gamma 1 7 7 1 1 1