Hello Prof. Paolo Giannozzi,Thank you for the response. Yes, indeed the
convergence is very smooth with Grimme-D2.But in case of vdW-DF2 functional
with ONCV pseudopotential using the parameter *input_dft='vdW-df2',* ph.x
does not converge at all. I am worried if I am using vdW-df2 incorrectly.
Just reduce the amount of vacuum: if you have too much of it, one
electron may decide to wandr of and cause all sort of troubles. Between
6 and 8 Å should be enough. Also, as Paola said, grimme-d2 cannot be the
cause as it is a purely ion-ion term.
On 9/21/20 1:12 PM, Dhvaneel Visaria
On Mon, Sep 21, 2020 at 1:13 PM Dhvaneel Visaria <
dhvaneel.visa...@iitb.ac.in> wrote:
this convergence issue did not arise for no vdW functional & Grimme-D2 cases
>
Grimme-D2 has *NO* effect whatsoever on the convergence of the
self-consistent procedure.
Paolo
> What could be the problem?
Hello Lorenzo Paulatto,
Thank you for your prompt reply.
I am still NOT able to achieve convergence for ph.x using vdW-DF2 even
after using finer k-point grids of 16x16x1 and 32x32x1, while this
convergence issue did not arise for no vdW functional & Grimme-D2 cases
with 12x12x1 k-point grid.
K_POINTS automatic
12 12 1 0 0 0
k-point grid which have a dimension multiple of 3 are a frequent cause
of troubles for graphene. Also, this is probably too coarse.
hth
--
Lorenzo Paulatto - Paris
___
Quantum ESPRESSO is supported by MaX
Hello users,
I have been trying to simulate graphene phonon dispersion using DFT-DF2 vdW
functional and ONCV pseudopotential.
I am using input_dft=‘vdw-df2’. I am getting nice convergence with scf
calculations using pw.x but I am unable to achieve convergence despite all
adjustments to the
