Dear Ajmalghan,
Some quick comments:
- Why do you use k point in the case of an isolated atom?? Well, that
should not matter, just that you are wasting computing time
- I guess that the spherical symmetry of the atom is broken; thus I would
use a non-cube cell, preferably the orthorhombic cell, with slightly
different lengths of the basis vectors of the unit cell. Then to break the
symmetry, you can use some randomisation of the initial wave functions.
And still, the convergence is probably going to be very difficult... You
can indeed try to fix the magnetisation; and I would reduce the
'mixing_beta' to something (very) small - in principle already at the
first step the electron density should be close to the self-consistent
one, bar the loss of sphericality and the randomised wave function
- Please remember that the scale of 'starting_magnetisation' is from -1
to +1, meaning that all the electrons are spin-polarised either up or
down, whereas in your case you only want to polarise the two valence
electrons out of the valence of the pseudo potential that seems to be 12
electrons
Well, Good Luck. :)
Greetings from Paris,
apsi
-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
Ari Paavo Seitsonen / [email protected] / http://www.iki.fi/~apsi/
Ecole Normale Supérieure (ENS), Département de Chimie, Paris
Mobile (F) : +33 789 37 24 25 (CH) : +41 79 71 90 935
On Sat, 9 Nov 2019, Ajmal Ghan wrote:
Hello all,
I have gone through all the archived discussion about cohesive energy
calculation.
I am trying to calculate the cohesive energy of Ti which is 4.85eV. But I am
getting 5.23 eV which is closer. But I have found from a previous discussion
here (
https://www.mail-archive.com/[email protected]/msg11410.html )
that, the final magnetization should be 2 Bohr mag/ cell at the end
of calculation for Ti and smearing contribution of energy should be 0.0Ry.
But I am getting to get 3.83 Bohr mag/cell and a significant smearing
contribution = -0.03295688 Ry.
Anyone help me to sort this. what should I change in the input?
here is my input,
&control
calculation = 'scf'
restart_mode = 'from_scratch'
pseudo_dir = '/work/shared/s-tih/pseudo/'
prefix = 'Tifree_deg1_50_8k_1'
wf_collect = .true.
tstress = .true.
tprnfor = .true.
forc_conv_thr = 1.0d-6
verbosity = 'high'
/
&system
ibrav = 1
celldm(1) = 20
nat = 1
ntyp = 1
ecutwfc = 50 //( I have performed convergence study. But since
degauss is reduced to 0.01, i increased ecut)
ecutrho = 400
nspin = 2
starting_magnetization(1) = 1 // I think, the final magnetisation
should be 2 bohr mag/ cell at the end of calculation.
nosym = .true /// I hope this is enough to
break the symmetry
nbnd = 100
occupations = 'smearing', smearing='mp', degauss=0.01D0
/
&electrons
diagonalization = 'cg'
mixing_beta = 0.7d00
conv_thr = 1.0d-8 // I used even higher convergence since
smearing is reduced.
/
ATOMIC_SPECIES
Ti 47.8670 Ti.pbe-spn-rrkjus_psl.1.0.0.UPF
ATOMIC_POSITIONS (crystal)
Ti 0.5 0.5 0.5
K_POINTS {automatic}
8 8 5 0 0 0
I don't really know this is the correct way to post a reply. All input is
welcome.
Thanks & Regards,
------------------------------------------------------------------------------------------------------
Ajmalghan MUTHALI
Post doctorate researcher
Laboratoire ICB
UMR 6303 CNRS-Université de Bourgogne
9 Avenue Alain Savary, BP 47870
F-21078 DIJON Cedex, France
Tel: +33-(0)7.69.28.19.91
Email : [email protected]
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
users mailing list [email protected]
https://lists.quantum-espresso.org/mailman/listinfo/users
