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Dear all,<br>
I am trying to relax YBCO (001) slabs with symmetric terminations (same on both sides) and a vacuum spacing of 7.5 Å on each side (7.5 Å – slab – 7.5 Å). I have tested all four possible surface terminations of YBCO, but none of the relaxations converge properly.
After m SCF cycles and n BFGS cycles, the SCF calculation starts to exceed 100 iterations.<br>
Moreover, the total energy values reported in the output file do not show a monotonic trend but oscillate instead. In contrast, the total force does decrease, from 0.9 down to about 0.09. I am using PBE-PAW pseudopotentials with the GGA approximation. The initial
geometry has been carefully verified.<br>
Spin and polarization effects are not included, as the slabs are symmetric. I have attempted several adjustments to improve convergence, including:<br>
- Reducing mixing_beta to 0.1</div>
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- Increasing degauss to 0.05 and changing the smearing type<br>
- Setting mixing_mode = 'local-TF'<br>
- Switching the diagonalization method to cg</div>
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However, the problem persists.<br>
Could you kindly help me understand what might be going wrong? My input and output files are attached below for reference.<br>
Thank you in advance for your support.</div>
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Best regards, </div>
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Michele De Angelis </div>
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PhD student, Dept. of Chemical Sciences and Technologies, Univesity of Rome Tor Vergata (Italy)</div>
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