derivation method for second_derivative of XC functionals

[Hanning Chen]

Dear CP2K users,

  I ran a TDDFPT calculation for excitation energies using PBE as my XC functionals. I encountered an error "Please provide a derivation method 12:50:04 ERRORL2 in pw_poisson_methods:pw_poisson_solve err=-300 12:50:06 ERRORL2 in xc:xc_calc_2nd_deriv err=-300  condition FAILED". I guess that was caused by a missing parameter for the second derivative of the XC terms. Please help me to resolve this issue.
 
 Thanks.

Hanning Chen

Department of Chemistry
Northwestern University
Evanston, IL 60208

[Axel]

On Apr 18, 2:22 pm, Hanning Chen <chenhann...@gmail.com> wrote:
> Dear CP2K users,
>
> I ran a TDDFPT calculation for excitation energies using PBE as my XC
> functionals. I encountered an error "Please provide a derivation method
> 12:50:04 ERRORL2 in pw_poisson_methods:pw_poisson_solve err=-300 12:50:06
> ERRORL2 in xc:xc_calc_2nd_deriv err=-300 condition FAILED". I guess that
> was caused by a missing parameter for the second derivative of the XC terms.

my guess is rather a missing implementation.
please post an input example.

axel.

[Axel]

On Apr 18, 2:22 pm, Hanning Chen <chenhann...@gmail.com> wrote:

> Dear CP2K users,
>
> I ran a TDDFPT calculation for excitation energies using PBE as my XC
> functionals. I encountered an error "Please provide a derivation method
> 12:50:04 ERRORL2 in pw_poisson_methods:pw_poisson_solve err=-300 12:50:06
> ERRORL2 in xc:xc_calc_2nd_deriv err=-300 condition FAILED". I guess that
> was caused by a missing parameter for the second derivative of the XC terms.
> Please help me to resolve this issue.

a little grepping through the sources reveals that you should have a
look at:
http://cp2k.berlios.de/manual/CP2K_INPUT/FORCE_EVAL/DFT/XC/XC_GRID.html#desc_XC_DERIV

i don't much about TDDFT, but my guess is that there is no analytical
2nd derivative
for the functional that you are using, so you'd have to use a
numerical method.

have you compared your input to existing test cases?

axel.

[Hanning Chen]

Dear Axel,

  Please see my input file below:

  &FORCE_EVAL
  METHOD Quickstep
  &DFT
    EXCITATIONS TDDFPT
     &TDDFPT
      INVERT_S Y
      KERNEL Y
      MAX_KV 60
      NEV 3
      OE_CORR SAOP
      REORTHO 2
      RES_ETYPE SINGLETS
      RESTARTS 2
      &XC
        &XC_FUNCTIONAL
          &PBE
          &END PBE
        &END XC_FUNCTIONAL
      &END XC
    &END TDDFPT
    &MGRID
      CUTOFF 280
    &END MGRID
    &QS
      EPS_DEFAULT 1.0E-10
    &END QS
    &SCF
      SCF_GUESS RESTART
      EPS_SCF 1.0E-5
      MAX_SCF 1000
      &OT
       MINIMIZER DIIS
      &END OT
    &END SCF
    &XC
      &XC_FUNCTIONAL PBE
      &END XC_FUNCTIONAL
    &END XC
  &END DFT
  &SUBSYS
    &CELL
      ABC 20.0 20.0 20.0
    &END CELL
    &COORD
    ...........................
     &END COORD
    &KIND Ag
     BASIS_SET DZV-GTH-LDA-q11-very-confined
     POTENTIAL GTH-PBE-q11
    &END KIND
  &END SUBSYS
&END FORCE_EVAL
&GLOBAL
  PROJECT ag_20
  RUN_TYPE SPECTRA
  PRINT_LEVEL MEDIUM
&END GLOBAL

Thanks.

Hanning

[Hanning Chen]

Axel,

  Yes. You are right. By putting

            
    &XC_GRID
          XC_DERIV SPLINE3_SMOOTH
    &END XC_GRID

  the error message went away. It seems that only a few derivative methods are supported by the XC functionals that I used.

  Thanks.

Hanning

[Juerg Hutter]

Hi

your first error message was related to a missing 2nd derivative
of a density functional. Your apparent fix however, is related
to the way the derivative of the density is computed.
I'm surprised that this had an impact. Maybe you did other changes?

The TDDFT code has not been worked on for three years.
The performance is not very good and the oscillator strength
calculation is missing.

regards

Juerg Hutter

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

[Hanning Chen]

Juerg,

  No, I did not make any changes besides the xc_derivative. I read the code, and it seems that only a few derivative methods are actually supported (the default one is unfortunately not). 

 

  Regarding the missing oscillator strength calculation, I may be able to fix it if the CP2K TDDFT module is based on Casida's SOS formula. Is it?

  Thanks.

Hanning

[Juerg Hutter]

Hi

sorry, I misinterpreted the error message. The problem was not the
2nd derivative of the XC functional but the 2nd derivative of
the electron density needed for the XC functional kernel.
This derivative is only available through plane wave derivatives
and not with spline derivatives.

The implemented TDDFT method is equivalent to Casida's method.
However, most implementations work in the MO basis, whereas
CP2K does the calculation in the AO basis.

regards

Juerg Hutter

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