Re: [D3q-discuss] question about group velocity unit

[Lorenzo P. <pa...@gm...>]

Hello David, unfortunately the unit of velocity is a bit of a mess. If 
you are reading it from a file produced by d3_tk.x using the option 
store_lw=.true. then the unit is actually Ry. But if you get it from 
d3_r2q.x then there is a RY_TO_CMM1 factor in it, which mean that you 
have to divide by ( 13.6058 * 8065.5 ). I'm going to ix this sooner or 
later... If you want to get rid of this factor you can just remove it 
from line 773 of of PROGRAM_r2q.f90 and recompile

regards

On 6/23/20 11:34 AM, david yang wrote:
> Dr. Paulatto,
> 
> I  have some doubt about the unit of group velocity in thermal code. The 
> manal says they in Rydberg (Rydberg bohr ? ) unit with the conversion of 
> (1.09*10^6) m/sec
> 
> If I use this My velocity comes out 407.581209999999998672*1.09*10^6, 
> which is too large to be correct.
> 
> Simply by taking the slope of the dispersion I get about ~3400 m/sec 
> which is in the right ballpark.
> 
> I would appreciate if you could point out my error here.
> 
> Thank you
> David
> 
> 
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-- 
Lorenzo Paulatto - Paris