Note the different lattice parameters in the 2 previously attached
struct files.
Am 05.12.2019 um 22:39 schrieb Tran, Fabien:
Hi,
Some time ago I did calculations on CsPbCl3 and I could reproduce
Jishi's results reasonably well except the one in the 1st column("GGA")
which is probably wrong. I got 0.70 eV (0.71 eV from Jishi) for
"GGA+SOC", 1.68 eV (1.59 eV from Jishi) for TB-mBJ and 2.86 eV (2.83 eV
from Jishi) for "present". The only special requirement that was needed
is a p1/2 LO on Pb. I used RKMAX=9 and de=10 in case.in1. The bug
reported here
http://zeus.theochem.tuwien.ac.at/pipermail/wien/2019-November/029882.html
is active but has very small effect of 0.01 eV for GGA+SOC. Try CsPbCl3
instead (struct and inso are attached).
FT
------------------------------------------------------------------------
*From:* Wien <wien-boun...@zeus.theochem.tuwien.ac.at> on behalf of
Mikhail Nestoklon <nestok...@mail.ru>
*Sent:* Thursday, December 5, 2019 8:21 PM
*To:* A Mailing list for WIEN2k users
*Subject:* [Wien] spin-orbit (PBE and mBJ) for perovskites
Dear wien2k community,
I plan to do some DFT calculation of inorganic perovskites using WIEN2k
(19.1 with some patches except the last one for RLO).
I’ve started from attempt to reproduce the values from Jishi et al.,
JPCC 118, 28344 (2014), but can not get the numbers given in Table 2
even for cubic CsPbI_3. The difference seem to stem from the spin-orbit.
What I did:
Using the file in attachment (I use the lattice constant given in table
1 and R_MT indicated in the text) I do
$ init_lapw -b -vxc 13 -rkmax 9.0 -lvns 6 -fftfac 4 && x kgen (14x14x14)
&& run_lapw -ec 0.00001 -cc 0.0001
I use -lvns 6, the difference with the result using standard value is
small, in Jishi et al. it is mentioned that l_{max}=10 which is default,
assuming they might have meant lvns I tried lvns=10, the difference with
lvns=6 is close to zero. I also tried to put Pb p3/2 orbitals to core
(if I put P1/2 to valence the result is strange, but this is a separate
question) and see no difference.
For k-mesh I check the convergence and see that for 14x14x14 the total
energy convergence is below 1mRy and GAP is below 1 meV which is fine,
so I am using this k mesh.
Then I check the RKMAX convergence. For Rmt*Kmax =9 without spin-orbit I
get the same number as in Table 2, but I see that this number is not
fully converged: if I increase RKMAX further the total energy decreases
for 8mRy and gap increases for almost 6 meV. I find it acceptable to use
RKMAX=12: only then it is <1mRy and ~1meV for total energy and gap
respectively. The gap with these numbers is 1.329meV which is 5 meV
different from Table 2, this difference is probably acceptable.
However, when I switch on the spin-orbit, the difference is huge. With
the default values (I only increase llmax, however it does not change
much) I get GAP about 0.269meV, which is almost 4 times different from
the value given in Jishi et al. Table 2. As the SO value depends on de
(in case.in1), I increase this parameter and check the value of GAP and
also spin-orbit splitting of conduction and valence band (difference
between energies of Gamma_8 and Gamma_7 in R point). GAP and spin-orbit
in conduction band fully (below 1meV) converge only when de=15. Still,
the band gap is 0.259eV which is too far from value given in Jishi et al.
The RLO (I tried to add it on Cs, as for Pb it should be useless [1])
does not help
With the same parameters I do the mBJ run (TB-mBJ). As expected, the gap
increases, but up to 0.722 eV which is two times different from the
value given in Jishi et al.
I did not try to change R_MT: I use the value given in their paper.
The fact that I do reproduce the number given for PBE without spin-orbit
indicates that I hardly did any mistake in the structure. However, the
difference in the numbers with spin-orbit is too large to be explained
by unconverged results, both on my and their side. Could you help me to
understand, how can I reproduce their results?
Thank you in advance.
Sincerely yours,
Mikhail Nestoklon
[1]
https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg17828.html
_______________________________________________
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
--
--------------------------------------------------------------------------
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
Email: bl...@theochem.tuwien.ac.at WIEN2k: http://www.wien2k.at
WWW:
http://www.imc.tuwien.ac.at/tc_blaha-------------------------------------------------------------------------
_______________________________________________
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html