# [Pw_forum] Using mixture of pseudo potential

Duy Le ttduyle at gmail.com
Tue May 31 19:29:36 CEST 2011

```On Tue, May 31, 2011 at 1:11 PM, Vi Vo <vovi47 at yahoo.com> wrote:
> Hi Pine,
>
> Thank you.  Yes, I know that I have to do different tests for ecutrho and
> ecutwfc, but my questions are different. I would like to know what is the
> default setting for ecutrho the code would assume. I restate my question as
> follows:
>
> If I forgot to specify the ecutrho, what default value of  ecutrho would the
> code assume for US PP?  (I guess it still uses the default
> ecutrho=4*ecutwfc).
>
> On the other hand, assuming I set the ecutrho=9*ecutwfc, does then the same
> value of ecutrho=8*ecutwfc also apply to NC PP, or does the value of
> ecutrho=4*ecutwfc will be used for NC PP.

If there is nothing changed, according to the QE manual, the default
factor of 4 does not depend on the type of potential.
Also, there is only one ecutrho in a single calculation, and it is
written in the output (most of parameters can be found in the output).

>
> Thank you,
>
--------------------------------------------------
Duy Le
PhD Student
Department of Physics
University of Central Florida.

"Men don't need hand to do things"

> Vi
>
>
> ________________________________
> From: lucking-pine <songsong19840614 at gmail.com>
> To: PWSCF Forum <pw_forum at pwscf.org>
> Sent: Mon, May 30, 2011 9:35:59 PM
> Subject: Re: [Pw_forum] Using mixture of pseudo potential
>
> Hi,
> In my way,I usually test ecutrho = X*ecutwfc using scf or relax.I look the
> result of total energy or enthalpy.
> Such as:
> 1.ecutwfc=47 ecutrho=400, total energy= -290.983
> 2.ecutwfc=47 ecutrho=380, total energy= -290.993
> So,I thought '2' is better than '1'.
>
> Bests,
> Pine.
> 2011/5/31 Vi Vo <vovi47 at yahoo.com>
>>
>> Dear All,
>>
>> In my calculation, I used a mixture of pseudo potentials, ie.
>> norm-conserving pp (NC pp)  for one element and ultrasoft pp (US pp) for
>> another.  If I don't specify ecutrho in the input, what will be the default
>> value for ecutrho for the ultrasoft pp.  I know that for NC pp, ecutrho =
>> 4*ecutwfc, but I do not know if the same value is used for US pp.  On the
>> other hand, if I specify ecutrho = 8*ecutwfc, then does the same value apply
>> to the NC pp.
>>
>> Thank you very much,
>>
>> Vi
>> University of Houston
>>
>>
>>
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>
>
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```