Dear Yun-Peng,
Plz try to decrease mixing and perform some convergence tests for your cutoff energy to remove the oscillation of the energy! In addition, this oscillation could also be caused by the unreasonable smearing methods for metals.
Bests
Fang
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Peter Cybertron> 2015-09-12 03:10:31 wrote:
Hi,
I am working in University of Florida as a postdoc.
I am exploring the spin-orbital calculations using pwscf, and I
encounter a very slow convergence like this:
> grep estimated scf.out
estimated scf accuracy < 0.00000004 Ry
... (100 similar lines)
estimated scf accuracy < 0.00000003 Ry
> grep "total energy" scf.out
...
total energy = -3667.91077719 Ry
total energy = -3667.91078176 Ry
total energy = -3667.91077642 Ry
total energy = -3667.91078300 Ry
Although the convergence of total energy seems OK (down to 0.00001 Ry ~
0.0001 eV = 0.1 meV), I still feel uncomfortable since I never encounter
such a problem without spin-orbit interactions.
I downloaded the ultrasoft and PAW pseudopotentials from PSLib and I am
using the PBE flavor of XC functional. The system I am studying is a two
dimensional magnetic insulator.
The parameters I am using are:
constrained_magnetization = 'total direction'
fixed_magnetization(3) = 0.0
lambda = 0.2
ecutwfc = 30.0 ,
ecutrho = 300.0 ,
occupations = 'smearing' ,
degauss = 0.005,
smearing = 'mv' ,
nosym=.true.
mixing_mode = 'local-TF' ,
mixing_beta = 0.9 ,
diagonalization = 'david' ,
Which parameter on earth keep my calculations non-converged?
Best,
Yun-Peng
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