[Wien] DOS plots for fixed spin moment LDA+U calculations

saurabh singh saurabhiitmandi at gmail.com
Sat May 21 05:46:08 CEST 2016


Dear All users,

Hope many people have faced similar problem in fixed spin moment DOS
calculations
I found problem in calculating DOS in fixed spin moment calculation. The
similar question asked long before
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg00449.html
 but there is no answer given for that.
In our case I do the LDA+U calculation I do follow the following step
before calculating DOS
1. init_lapw
2.runsp_lapw  -cc 0.0001
3. runsp_lapw -orb -cc 0.0001
4. runfsm_lapw -orb -m 8 -cc 0.0001

I get total spin magnetic moment in unit cell 8.0001 μB.  I do follow the
instruction of user manual where it is recommended that one should run x
lapw1 -orb -up before calculating the DOS. So i did it then i executed
following command
x lapw2 -qtl -up
configure_init_lapw
x tetra -up

the above three command with dn. I calculated total DOS in present case.
The problem I faced that

1. As per the manual "only case.vectordn is ok, but case.vectorup is NOT
the proper up-spin vector and MUST NOT be used for the calculations of QTLs
(and DOS). It must be regenerated by x lapw1 -up ". Its ok then why if I
calculate first the dos for dn spin and then follow the required correction
of case.vectorup by running the x lapw1 -up command it gives two different
fermi level in qtlup and qtldn file. This is done by the following steps :
After SCF convergence
x lapw2 -qtl -dn
configure_init_lapw
x tetra -dn
x lapw1 -orb -up
x lapw2 -qtl -up
x tetra -up

I also integrated DOS (case.dosevup/dn) for up and dn spin and found the
difference in the integrated value at Fermi level (0 eV) is  nearly 3.07.
If the above steps is right it should be nearly 8
2. If I follow the following steps
x lapw1 -orb -up
x lapw2 -qtl -up
configure_init_lapw
x tetra -up
x lapw2 -qtl -dn
x tetra -dn

Then I got same Fermi level in both the qtlup and qtldn file. But again the
difference at  Fermi level (i.e. 0 eV) in integrated value of up and down
spin DOS is nearly 6.13, where as it should be nearly 8.

I do not understand why this is happening. Can any one give the proper
steps of finding the DOS for the fixed spin moment calculation. Where I am
doing the mistakes or which procedure followed by me is wrong. I will be
very grateful to you.
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