[QE-users] Naive questions about input files 2D perovskite phonon calculation

[Lorenzo Bastonero]

Dear Hy Lu,

It seems to me that your procedure and inputs (at least for pw.x) are correct.

If I am not mistaken, the correction will work along the z direction, so make sure that you have your vacuum direction correctly aligned.

Then, just note that the (non-resonant) Raman intensities can be obtained only using LDA and norm conserving pseudo in ph.x. 
An alternative way in this case could be finite differences. A possible package you can use for this case is the one I developed (search for aiida-vibroscopy). There are also others, but since you cell seems rather big, it seems that could be convenient to use finite field (as I use in the code), instead of finite dielectric tensors.

If you are interested in the resonant case, there is a new package for that, called QERaman. I believe it works also for PBE, but only norm-conserving pseudo (not super sure, but it won’t be a problem for you anyways).

HTH,
Lorenzo

Inviato da iPhone

> Il giorno 16 ott 2023, alle ore 10:25, ludwigboltzmann.sc10 at nycu.edu.tw ha scritto:
> 
> 
> Dear users:
> 
> I am going to calculate do phonon calculation and Raman spectra calculation of 2D perovskite (only at Gamma point), 
> 
> My procedure is like this: doint: vc-relax & scf→phonon calculation→dynmat
> 
> 1.Should I put assume_isolated='2D' in my vc-relax & scf input?
> Ref: q-e/PHonon/examples/example17/reference
> 
> Cause I'm not quite sure what is it mean here.
> The extension of DFPT to two dimensional crystals, in "particular gated two-dimensional heterostructure", 
> 
> Ref: https://www.quantum-espresso.org/wp-content/uploads/2022/03/ph_user_guide.pdf
> 
> 
> Below is my vc-relax input example.
> 
> &control
>     calculation = 'vc-relax'
>     restart_mode='from_scratch'
>     prefix ='2D_perovskite'                              !test100tri
>     pseudo_dir = " pseudo_dir"
>     outdir=" outdir"
> /
> &system
>     ibrav=14,                   !triclinic
>   celldm(1)=16.13770350000000,celldm(2)=0.99156550541343,celldm(3)=1.87963300392941,celldm(4)=-1.94983007225937e-03,celldm(5)=0.13312393987385,celldm(6)=5.68819706737211e-04
>     nat=94, ntyp=5,
>     ecutwfc=150
>     ecutrho=600
>     vdw_corr=grimme-d2
> /
> &electrons
>     conv_thr=1e-14
> /
> ATOMIC_SPECIES
> Sn    118.71000  Sn_ONCV_PBE-1.2.upf
> H       1.00784  H_ONCV_PBE-1.2.upf
> C      12.011    C_ONCV_PBE-1.2.upf
> I     126.90447  I_ONCV_PBE-1.2.upf
> N      14.0067   N_ONCV_PBE-1.2.upf
> ATOMIC_POSITIONS (crystal)
> I             0.8103731347        0.6896489973        0.4992596099
> I             0.1896268653        0.3103510028        0.5007403901
> ...
> 
> K_POINTS (automatic)
>   5 5 1 1 1 1
> 
> 
> 
> Sincerely,
> 
> National Yang Ming Chiao Tung University
> HY Lu
> 
> 
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