[Q-e-developers] Defining the anti-ferromagnetic case

[Gautam Gurung]

Dear all QE users,
I am trying to calculate the ground structure of Mn3Ir. To define the non-collinear antiferromagnetic feature such that the 111 plane form the kagome lattice, I think I  have to use different kind of Manganese atoms with different magnetization orientation.  So, I defined the input  for quantum espresso as;
======================Input====================

&control
    calculation='scf'
    restart_mode='from_scratch',
    pseudo_dir = './pseudo/',
    outdir='./tmp/'
    prefix='Mn3Ir'
    wf_collect=.true.
    etot_conv_thr=1.0D-8
    tprnfor=.true.
    tstress=.true.
/
&system
    ibrav = 1, celldm(1) =7.1526134, nat= 4, ntyp= 4,
    ecutwfc =180,ecutrho=720
    lspinorb=.true.,
    noncolin=.true.,
starting_magnetization(2) = 0.6
  angle1(2)=114.09
  angle2(2)=114.09
starting_magnetization(3) = 0.6
  angle1(3)=114.09
  angle2(3)=35.26
starting_magnetization(4) = 0.6
  angle1(4)=35.26
  angle2(4)=114.09
occupations='smearing', smearing='cold', degauss=0.03
/
&electrons
    startingwfc='random'
    conv_thr=1.0e-10
/
ATOMIC_SPECIES
Ir 192.217 Ir.rel-pbe-spfn-rrkjus_psl.1.0.0.UPF
Mn1 54.938045 Mn.rel-pbe-spn-rrkjus_psl.1.0.0.UPF
Mn2 54.938045 Mn.rel-pbe-spn-rrkjus_psl.1.0.0.UPF
Mn3 54.938045 Mn.rel-pbe-spn-rrkjus_psl.1.0.0.UPF

ATOMIC_POSITIONS
Ir  0.0 0.0 0.0
Mn1 0.5 0.0 0.5
Mn2 0.0 0.5 0.5
Mn3 0.5 0.5 0.0

K_POINTS (automatic)
18 18 18 0 0 0
============================================
Is this way correct? If I use nat=7 and ntyp=7 then by symmetry even I define Mn as different  atoms with different magnetization orientation and starting_magnetization=-0.6 ,I think the QE use the concept of equivalent atoms and give an error.  How should I define my input? 

In addition to this, I did not find any tutorial for the constrained magnetization in the QE link. Is there any tutorial file for the calculation of the constrained magnetization? How can we set the value of the lambda in such cases?
To define the constrained magnetization=’total direction’, what should I do to define that there is an external field in the 010 direction?

Thank you.


Gurung
University of Nebraska Lincoln

Sent from Mail for Windows 10

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