[QE-users] Fw: Problem with SOC

[David Kostov]

 Dear Guido
Thank you for your valuable comment. I tried your advises and could get the system get converged in the x direction magnetization with following options. 


&SYSTEM
    nat = 6,
    ntyp = 2,
    degauss = 0.12,
    ibrav = 0,
    ecutwfc = 140,
    nbnd=50,
    occupations = 'smearing',
    smearing = 'mp',
    starting_magnetization(1)=0.1,
    starting_magnetization(2)=0.0,
    constrained_magnetization= 'atomic',
    angle1=90,
    angle2=0,
    noncolin= .true.
    lspinorb= .true.
 /


However I have got to know from previous pw_forum's posts that with such a constrained calculation, the constrained energy in the convergence needs to be very close to zero. But in my case it is not. (last iteration in the vc-relaxed run copied below)

     total magnetization       =     5.77     0.00     0.00 Bohr mag/cell
     absolute magnetization    =     5.86 Bohr mag/cell
     lambda                    =       1.00 Ry

     iteration # 24     ecut=   140.00 Ry     beta=0.30
     Davidson diagonalization with overlap
     ethr =  1.00E-13,  avg # of iterations =  2.1
     constraint energy (Ryd) =     11.31368053

Can you/someone else please let me know whether I can go forward with this configuration or it needs to change. 

I do not have any idea what to do to reduce constrained energy in this system, please advice me.
Thank youDavid PhD student 
Okayama University



    On Saturday, November 2, 2019, 6:23:28 a.m. CST, Guido Menichetti <menichetti.guido at gmail.com> wrote:  
 
 Dear Kostov
First of all, please add your signature (affiliation/university/position)
About the difference between SP and SOC calculation:The magnetism in SOC calculation in non-collinear so if you give to the code just the magnitude of the magnetic moments it could not be enough to reach the right/desired magnetic configuration. If you look for a specific magnetic configuration you could also try the "constrained magnetization".
Try to add a guess on the starting angles (of the magnetic moments)
About the  vc-relax: It could happen if the relaxed structure is far from the starting one. 
Are you in the same magnetic configuration?Try the relaxation again.
HTHBestG.
Il giorno sab 2 nov 2019 alle ore 03:31 David Kostov <dkca at yahoo.com> ha scritto:

 I am still waiting for a reply for this issue. Thank you in advance.




   ----- Forwarded Message ----- From: David Kostov <dkca at yahoo.com>To: Quantum ESPRESSO Users Forum <users at lists.quantum-espresso.org>Sent: Wednesday, October 30, 2019, 2:43:25 p.m. CSTSubject: Problem with SOC
 Dear QE community
I want to study my FM system with and without SOC included. Thus I tried geometry optimization, vc-relax, for the two cases.
In the FM without SOC, I got the following magnetization. In my system, there are two magnetic atoms. So I think one atom will have 6.48/2= 3.24 Bohr mag/cell.
  total magnetization       =     6.37 Bohr mag/cell
  absolute magnetization    =     6.48 Bohr mag/cell

However, in the FM+SOC, the magnetization results for the final structure in the vc-relax process is zero. 

total magnetization       =    -0.00    -0.00     0.00 Bohr mag/cellabsolute magnetization    =     0.00 Bohr mag/cell

I am little bit not clear with this situation. Can someone please clarify me what this results tells me  in the FM+SOC case ? (is this converging to a NM case? I mean since absolute mag=0?)
But in the input script, I defined in a way the system is FM.
input in the FM+SOC.................................
 &SYSTEM
    nat = 6,
    ntyp = 2,
    degauss = 0.12,
    ibrav = 0,
    ecutwfc = 140,
     nbnd=50,
    occupations = 'smearing',
    smearing = 'mp',
    starting_magnetization(1)=0.1,
    starting_magnetization(2)=0.0,
    noncolin= .true.
    lspinorb= .true.............................................................................................


The other problem I am facing is when I check the scf calculation with the converged final lattice and atomic coordinates (of course with the same input SYSTEM data above), the pressure is very high at the end, around 40GPa. I m not sure what is wrong with the calculation.
Thank you in advance
D.






  _______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
users mailing list users at lists.quantum-espresso.org
https://lists.quantum-espresso.org/mailman/listinfo/users


-- 
***************************************

Guido Menichetti
Post-Doc researcher in Condensed matter physics
Istituto Italiano di Tecnologia
Theory and technology of 2D materials
Address: Via Morego, 30, 16163 Genova
Email:  guido.menichetti at iit.it             guido.menichetti at df.unipi.it        
             menichetti.guido at gmail.com
****************************************_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
users mailing list users at lists.quantum-espresso.org
https://lists.quantum-espresso.org/mailman/listinfo/users  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20191105/937a6e30/attachment.html>