[Pw_forum] similar to WAVECAR and CHGCAR in VASP

[Marzari Nicola]

Hi Lorenzo,

I'd (respectfully) disagree re the extremely expensive - quite the opposite.

The cost of a vasp licence is comparable to the cost of one workstation, anywhere in the world, or two weeks of the full cost of a postdoc in the us or europe. Sometimes it might be difficult to raise those funds, but the personnel costs of the people running the codes, followed by the costs of the computational resources, are most often the real cost/expense/investment. Of course, there are exceptions, but for most groups worldwide one needs to look at the overall picture when assessing cost.

This is to say that cost of the licence is not a good reason to choose one code over the other.

Nicola



Sent from a tiny keyboard...

> On 04 Aug 2015, at 10:22, Lorenzo Paulatto <lorenzo.paulatto at impmc.upmc.fr> wrote:
> 
>> On Monday, August 03, 2015 07:29:56 PM Amir wrote:
>> When we run a calculation in VASP, it makes WAVECAR and CHGCAR files that
>> can be used as input file for further calculations, for example, if we want
>> to increase the number of k points or increase the cut off energy. It is
>> also very useful, especially, if you want to continue a relaxation without
>> doing the first loop of self-consistent calculation since we already have
>> the charge density for the initial structure. Is there such thing in QE?
> 
> Dear amir,
> You've chosen the worst possible way to describe what you need: Analogy to the 
> internal features of an extremely expensive competing code. 
> 
> In pw.x there is normally no way to restart a calculation with a different 
> cutoff, however if the code finds an existing charge density file when 
> restarting, it will use it.
> 
> You may also look at calculation="nscf" or calculation="bands". 
> 
> kind regards
> 
> -- 
> Dr. Lorenzo Paulatto
> IdR @ IMPMC -- CNRS & Université Paris 6
> +33 (0)1 44 275 084 / skype: paulatz
> http://www.impmc.upmc.fr/~paulatto/
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> 4 place Jussieu 75252 Paris Cédex 05
> 
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