[CPMD-list] TDDFT force calculation not compatible with NLCC pseudopotential?

[Juerg Hutter]

Hi

if I recall correctly, we never tested TDDFT gradients
with NLCC. It might be a good idea to see if you get
into the same problems using one of the Goedecker PP.
This test should be possible with a reasonable cutoff.

regards

Juerg Hutter

----------------------------------------------------------
Juerg Hutter                   Phone : ++41 44 635 4491
Physical Chemistry Institute   FAX   : ++41 44 635 6838
University of Zurich           E-mail: hutter at pci.uzh.ch
Winterthurerstrasse 190
CH-8057 Zurich, Switzerland
----------------------------------------------------------


On Tue, 26 Jun 2007, Xiulin Ruan wrote:

> Dear Axel and Professor Hutter,
>
> Thanks for your replies. Here I wanna add a little more information to make
> our problem clearer. This problem arose when we was trying to do the excited
> state geometry optimization. However, the TDDFT single point energy
> calculations with the Ti_MT_LDA_NLCC pseudopotential worked pretty well, and
> the calculated vertical excitation energies were good. This looks a little
> surprising to us since geometry optimization is like a series of iterated
> single point energy calculations. Hope you can help on this problem.
>
> Thanks,
>
> Xiulin
>
>
>> -----Original Message-----
>> From: cpmd-list-bounces at cpmd.org [mailto:cpmd-list-bounces at cpmd.org] On
>> Behalf Of Juerg Hutter
>> Sent: Tuesday, June 26, 2007 6:38 AM
>> To: Hua Bao
>> Cc: cpmd-list at cpmd.org
>> Subject: Re: [CPMD-list] TDDFT force calculation not compatible with NLCC
>> pseudopotential?
>>
>> Hi
>>
>> one of the problems of TDDFT geometry optimization is
>> that you might get into areas where the geometry is far
>> of the optimal ground state geometry. In those cases
>> (restricted) Kohn-Sham calculations for the ground state
>> are difficult and might result in unreasonable
>> electronic structures.
>>
>> I would check the ground state result, especially
>> HOMO and LUMO energy for your last geometry.
>>
>> regards
>>
>> Juerg Hutter
>>
>> ----------------------------------------------------------
>> Juerg Hutter                   Phone : ++41 44 635 4491
>> Physical Chemistry Institute   FAX   : ++41 44 635 6838
>> University of Zurich           E-mail: hutter at pci.uzh.ch
>> Winterthurerstrasse 190
>> CH-8057 Zurich, Switzerland
>> ----------------------------------------------------------
>>
>>
>> On Mon, 25 Jun 2007, Hua Bao wrote:
>>
>>> Dear All,
>>>
>>> I am calculating Ti[H2O]6 cluster with TDDFT. The spectra result is
>> pretty
>>> good. However, TDDFT MD result is not reasonable. It has following
>> warning
>>> messages while calculating the TDDFT forces (also see my last post),
>>>
>>> CALCULATION OF TDDFT FORCES
>>>
>>> CPU TIME FOR INITIALIZATION OF LINEAR RESPONSE:     0.17 SECONDS
>>> WARNING! First order density integral (R space)   1.40622137E-06
>>> WARNING! First order density integral (R space)   3.17749222E-04
>>>   NFI      GEMAX     CNORM         ETOT(2)        DETOT     TCPU
>>>     1***********547.690471****************    0.000       37.130
>>> WARNING! First order density integral (R space)   1.05641421E-03
>>>
>>> And the force is unreasonable (10^3 order). I am using Ti_MT_LDA_NLCC
>>> pseudopotential and LDA functional. If I don't specify the
>> pseudopotential
>>> option of NLCC, then it will run normally. However, the electron spectra
>>> result is not good. Is there any incompatible between NLCC and TDDFT
>> force
>>> calculation?
>>>
>>> If it is the case, can anyone give me some suggestions on choosing a
>> proper
>>> pseudopotential of Titanium? There is only NLCC pseudopotential for Ti
>> in
>>> CPMD package.
>>>
>>> Thanks,
>>> Hua Bao
>>>
>>> Graduate Student
>>> School of Mechanical Engineering
>>> Purdue University
>>> Office Tel: (765) 494-6944
>>>
>>>
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>
>