Hello,
if I remember correctly, a k-point grid that includes the K point
invariably causes problems in graphene. This is because graphene is
metallic at this point, its Raman tensor diverges.
To have the Raman tensor correctly, you should use a much larger grid
and take care to not include the K-point, i.e. the grid dimension must
not be a multiple of 3. I recommend trying 64x64x1
regards
On 4/19/20 4:58 PM, [email protected] wrote:
I am having an issue computing the Raman spectrum for graphene. The
output is as follows:
<#>
# mode [cm-1] [THz] IR Raman depol.fact
1 -4834.05 -144.9213 0.0000*************** 0.7500
2 -0.00 -0.0000 0.0000*************** 0.7500
3 -0.00 -0.0000 0.0000*************** 0.7500
4 0.00 0.0000 0.0000*************** 0.7500
5 0.00 0.0000 0.0000*************** 0.7500
6 0.00 0.0000 0.0000*************** 0.7500
I did the relaxation and scf calculations using LDA, with a cutoff of
120 Ry, and force convergence of 1.0d-6, etot convergence of 1.0d-8, and
electronic convergence of 1.0e-10. I used a 30 30 1 kpoint grid and used
the grimme-d2 van der waals option. I also did not include smearing as
the phonon calculation yelled at me when I tried. I am using a two atom
cell, is this the problem?
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Lorenzo Paulatto - Paris
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