[QE-users] Raman output displaying stars

[grayj6]

# mode   [cm-1]    [THz]      IR          Raman   depol.fact
     1     -0.00   -0.0000    0.0000  30489332.8099    0.7500
     2     -0.00   -0.0000    0.0000         0.0000    0.7500
     3     -0.00   -0.0000    0.0000   7840022.8339    0.7500
     4      0.00    0.0000    0.0000         0.0000    0.7500
     5      0.00    0.0000    0.0000  70167809.6856    0.7500
     6   1600.81   47.9912    0.0000 108497165.3036    0.7500

Thank you. I have better results now, but the cm^-1 column is mostly 
zeroes.

On 2020-04-20 03:54, Lorenzo Paulatto wrote:
> 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, grayj6 at rpi.edu 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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