[Wien] Lapw0 parallel

[Gavin Abo]

In the WIEN2k 14.2 userguide [ 
http://www.wien2k.at/reg_user/textbooks/usersguide.pdf ] on page 80, it 
says:

/lapw0_mpi is parallelized over the number of atoms and with a parallel 
FFT, which is important in case you have large FFT grids. This method 
leads to good scalability as long as there are more atoms than processors./

As the second sentence above says, you can use 128 cores or less, but 
you should NOT use more cores than that.

In the post at that link, the structure had 8 atoms, but the .machines 
file was set to use 48 cores.  So the .machines file needed to be 
changed to not use more than 8 cores.

On 6/24/2016 7:53 AM, Wangwei Lan wrote:
> Dear WIEN2K user,
>
> I am now doing parallel calculation on lapw0, one thing I notice is 
> that, lapw0 is only paralleled over atoms, as discussed here
>
> http://www.mail-archive.com/wien%40zeus.theochem.tuwien.ac.at/msg06622.html
>
>
> In my case, I have a 4x4x4 supercell, and in total 128 atoms, so that 
> requires 128 cores. However, it's seems impossible for me to use so 
> many cores at this time. Is my understanding correct on this issue?
>
> Does anyone have a good idea on how to solve this problem? Thanks in 
> advance.
>
> Best Regards
> Wangwei Lan
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