[QE-users] Few basic questions for various combinations of &SYSTEM control

[rekha sharma]

Dear Experts,

I want to simulate MoS2 and similar 2D systems with ferromagnetic
calculation with and without SOC in  spin-polarised situation and a
collinear ferromagnetic case.
Below is my research that I have done before posting this query here:

example07 tells me to include
    lspinorb=.true.,
    noncolin=.true.,  to perform SOC with fully relativistic PPs.

from example11,  I came to know that, if I insert
    starting_magnetization(1)=0.5, in SYSTEM control then it will be
ferromagnetic.
Additionally, we need to define "nspin=2" to do a spin-polarised
calculation.

Therefore, for a  ferromagnetic+SOC (spin-polarised)  calculation, the
&SYSTEM control will be
 &SYSTEM
lspinorb=.true.,
noncolin=.true.,
starting_magnetization(1)=0.5,
nspin=2

But then it becomes non-collinear (example11: QE-6.4.1), NO??

>From here I have few basic question that needs answer:
1. Is, my below QE.in file is correct for  ferromagnetic+SOC+Spin-polarised
case?
2. Can we do vc-relax with ferromagnetic+SOC+Spin-polarised?
3. What else I need to do if I want to perform a collinear calculation?

I want to test spin-polarised ferromagnetic, spin-polarised
ferromagnetic+SOC and collinear ferromagnetic with PBE and PBE+HSE on 2D
systems one which is under mentioned:

I have prepared below structure for ferromagneitc+SOC+spin-polarised
calculation.

&CONTROL
                 calculation = 'scf'
                restart_mode = 'from_scratch'
                      outdir = './tmp'
                  pseudo_dir = '.'
                      prefix = 'pwscf'
                     disk_io = 'none'
                   verbosity = 'default'
               etot_conv_thr = 0.0001
               forc_conv_thr = 0.001
                       nstep = 400
                     tstress = .true.
                     tprnfor = .true.
 /
 &SYSTEM
                       ibrav = 0
                         nat = 4
                        ntyp = 2
                     ecutwfc = 60
                     ecutrho = 480
                    vdw_corr = 'Grimme-D3  ! layered system

                 occupations = 'smearing',    ! Spin-polarised
                    smearing = 'mv',
                     degauss = 0.01,

                       nspin = 2,                ! Spin-polarised
   starting_magnetization(1) = 0.6  ! Ferromagneitc
   starting_magnetization(2) = 0.6    ! Ferromagneitc

                   lspinorb = .true.,        ! SOC
                   noncolin = .true.,        !SOC


 /
 &ELECTRONS
            electron_maxstep = 200
                    conv_thr = 1.0D-7
              diago_thr_init = 1e-4
 /
&IONS
                ion_dynamics = 'bfgs'
 /

ATOMIC_SPECIES
   Mo   95.9400000000  Mo.rel_pz.upf
    S   32.0650000000  S.upf

ATOMIC_POSITIONS crystal
Mo      0.99980000000000      0.99967000000000      0.00140000000000
Mo      0.41010000000000      0.50033000000000      0.99860000000000
 S      0.76020000000000      0.47161000000000      0.12240000000000
 S      0.27390000000000      0.96106000000000      0.16787000000000
 S      0.64960000000000      0.02839000000000      0.87760000000000
 S      0.13600000000000      0.53894000000000      0.83213000000000

K_POINTS automatic
3  4  1   0 0 0

CELL_PARAMETERS {bohr}
    10.77143895744817      0.00000000000000      0.00000000000000
     0.00000000000000      6.06413116043003      0.00000000000000
     1.28290955440224      1.40801058817318     18.81430995418407

I have gone thorough mailing list and example06,07,11,12 before writing
this email.

[1].
https://www.mail-archive.com/users@lists.quantum-espresso.org/msg17101.html

Thank you very much for any help.


Best wishes

Ms. Rekha
Teaching Assistant,
Department of Physics
RK college, Jaipur, India
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