[Pw_forum] Documentation for fd_ef.x

[Andrew Supka]

Not sure why but the two attached files did not appear to attach properly.
Here they are as text instead.

fd_ef.x input:

&inputfd
   prefix='_test'
   de_eps=0.001
   npol_eps=2
/
DIELECTRIC_TENSOR
   -1.300688044469352e-07 -5.025345268956680e-07 4.814153579958187e-07 !
0.000 0.000 0.000 ! 0
   -2.890345666111305e-03 8.841829526340080e-01 2.890319861455298e-03 !
-0.001 0.000 0.000 ! -x
   -8.841805432643650e-01 2.890279870502680e-03 2.890458257746116e-03 !
0.001 0.000 0.000 ! +x
    2.890277929333495e-03 -2.890413576240535e-03 -8.841803319166400e-01 !
0.000 -0.001 0.000 ! -y
    8.841807604606760e-01 -2.890494655088760e-03 -2.890312247424385e-03 !
0.000 0.001 0.000 ! +y
   -2.890316211626032e-03 2.890181959191641e-03 8.841830541079900e-01 !
0.000 0.000 -0.001 ! -z
    2.890270571013795e-03 -8.841828609575770e-01 -2.890215625887111e-03 !
0.000 0.000 0.001 ! +z

pw.x input:

&control
   calculation = 'scf',
   pseudo_dir = './',
   outdir = './',
   nstep = 200,
   prefix = '_finite_field.06',
   wfcdir = './',
   max_seconds = 12905,
   restart_mode = "from_scratch",
   lelfield = .TRUE.,
   nberrycyc = 3,
   tprnfor = .TRUE.,
/
&system
   ibrav = 2,
   celldm(1) = 12.3400416494,
   nat = 2,
   ntyp = 2,
   ecutwfc = 50.,
   ecutrho = 500,
   celldm(2) = 1.0,
   celldm(3) = 1.0,
   celldm(4) = 6.12323399574e-17,
   celldm(5) = 6.12323399574e-17,
   celldm(6) = 6.12323399574e-17,
/
&electrons
   diagonalization = 'david',
   mixing_mode = 'plain',
   mixing_beta = 0.7,
   conv_thr = 1.0d-10,
   electron_maxstep = 200,
   efield_cart(1) = 0.0,
   efield_cart(2) = 0.0,
   efield_cart(3) = 0.001,
/
&ions
/
&cell
   cell_factor = 2.0,
/
ATOMIC_SPECIES
Pb 207.2 Pb.pbe-dn-kjpaw_psl.0.2.2.UPF
Te 127.6 Te_pbe_v1.uspp.F.UPF
ATOMIC_POSITIONS {crystal}
Pb 0.000000000000000000 0.000000000000000000 0.000000000000000000 1 1 1
Te 0.500000000000000000 0.500000000000000000 0.500000000000000000 1 1 1
K_POINTS {automatic}
10 10 10 1 1 1




On Feb 25, 2018 6:32 PM, "Andrew Supka" <supka1ar at cmich.edu> wrote:

> Robert,
> Lorenzo is correct in that it's reasonably expensive to do it with
> fd_ef.x.
>
> I'm attaching two files:
>
> 1.) fd_ef.x input
> 2.) An scf file for one of the polarization directions needed.
>
> The seven directions and their order are mentioned in the fd_ef.x input
>
> Depending on the symmetry of your system you can reduce the number of
> polarization directions you need to actually calculate.
>
> You will have to run the scf calculations for each polarization direction
> and copy from each output the converged values (the last one) for the
> electronic dipole:
>
> Electronic Dipole on Cartesian axes
>            1 -3.224342350515147E-003
>            2 3.224063842650654E-003
>            3 0.889627066087568
>
> Into the fd_ef.x input.
>
> Keep in mind that the example scf input is just an example and you should
> test the scf input parameters (particularly the kp grid) to verify they're
> adequate for your system.
>
> Good luck!
>
> Andrew Supka
> PhD Student
> Central Michigan University
>
> On Feb 25, 2018 5:33 PM, "Lorenzo Paulatto" <paulatz at gmail.com> wrote:
>
>
>
> On 02/25/2018 07:58 PM, Robert Wexler wrote:
> > force constants. Since ph.x, to the best of my knowledge, cannot handle
> > vdW corrections,
>  > ... QE version 5.1.
>
> The current version ph.x can handle vdW corrections with no problems,
> but you'll have to upgrade, because v5.1 is very old.
>
> To get epsilon doing finite derivatives from modern theory of
> polarization, via fd_ef, or not by hand, the only difficulty are the
> units of measure, is not very efficient it would probably take a billion
> k-points. If you insist, and manage to do it, please send us a working
> example.
>
> hth
>
>
> --
> Lorenzo Paulatto - Paris
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>
>
>
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