[Pw_forum] question on the lplot_drho variable of turbo_davidson

[Giuseppe Mattioli]

Dear Giovanni

> Qualitatively I think this lplot_drho is what you are looking for, as long
> as you can make sure that the frequency of excitation at which you plot the
> response density is corresponding to the excitation you are aiming at.

Ok, thanks. I 'm going to give it a try and see what happens. But I'm already facing myself with some problems:

 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
     task #        25
     from davcio : error #        20
     error while writing from file "/home/mattioligi/cocat/test_tddft/5.2.1/l0/run/tmp/l0.d0psi.326"
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
     task #        21
     from davcio : error #        20
     error while writing from file "/home/mattioligi/cocat/test_tddft/5.2.1/l0/run/tmp/l0.d0psi.322"
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
     task #         0
     from davcio : error #        20
     error while writing from file "/home/mattioligi/cocat/test_tddft/5.2.1/l0/run/tmp/l0.d0psi.31"
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

this is my input file, if you want to give advice. I'm running on a 32 cores/64 GB machine, so I hope this is not a RAM problem because the test 
molecule I'm investigating is relatively small (42 atoms in a 40 a.u.^3 box with US pseudopotentials and 40/320 Ry cutoffs. I can send you further 
details, if you need them).

&lr_input
    prefix="l0",
    outdir='/home/mattioligi/cocat/test_tddft/5.2.1/l0/run/tmp/',
    restart=.false.
/
&lr_dav
    num_eign=1
    num_init=2
    num_basis_max=20
    residue_conv_thr=1.0E-4
    start=0.0
    finish=1.0
    step=0.0002
    broadening=0.005
    reference=0.1
    p_nbnd_occ=10
    p_nbnd_virt=10
    lplot_drho=.true.
    poor_of_ram=.false.
    poor_of_ram2=.false.
/

>  I
> did not see anything strange that the  response density is symmetric
> containing both negative and positive part.

Neither I in the case of a symmetric water molecule. I was only trying to say that the plotted quantity could not be the total density of the S1* 
state because it contains a negative and a positive part. In a "naif" view I would say that if a given electronic transition is almost totally 
projected on the HOMO-->LUMO vector, then the lplot_drho plot should show charge depletion on the HOMO and charge accumulation on the LUMO.

> Besides, can you tell me where did you find the h2o-plotrho example?

I've found it here, after manual unpacking of tddfpt-5.2.1.tar.gz

~/Espresso/5.2.1/TDDFPT/Examples

Thank you again for your help!

Best Wishes

Giuseppe

On Thursday, January 28, 2016 02:17:22 PM xiaochuan Ge wrote:
> Dear Giuseppe,
> 
> Qualitatively I think this lplot_drho is what you are looking for, as long
> as you can make sure that the frequency of excitation at which you plot the
> response density is corresponding to the excitation you are aiming at. I
> did not see anything strange that the  response density is symmetric
> containing both negative and positive part. Why do you think it is wired?
> Besides, can you tell me where did you find the h2o-plotrho example?
> 
> Best,
> 
> ===================
> Dr. Xiaochuan Ge (Giovanni)
> Center for Functional Nanomaterials
> Brookhaven national laboratory
> ===================
> 
> On 28 January 2016 at 11:20, Giuseppe Mattioli <giuseppe.mattioli at ism.cnr.it
> 
> > wrote:
> > 
> > 
> > Dear All
> > What is exactly the "response charge-density at each resonance" which can
> > be calculated with turbo_davidson.x? Let me rephrase the question in another
> > way: I want to calculate the charge displacement between the S0 (ground
> > state) and S1* (first singlet excited state) of a given molecule. So I need
> > the
> > total charge density of S0 (easy to compute with pp.x) and the total
> > charge density of S1*. I do not know how to compute the latter quantity. I
> > was
> > wondering whether lplot_drho=true plots such a quantity, but I believe it
> > does not, because the h2o-plotrho example produces a cube file containing a
> > symmetric positive and negative charge distribution. Or is this lplot_drho
> > result exactly what I'm looking for?
> > Please enlighten me and thank you in advance.
> > Giuseppe
> > 
> > ********************************************************
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> > ********************************************************
> > 
> >    Giuseppe Mattioli
> >    CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
> >    v. Salaria Km 29,300 - C.P. 10
> >    I 00015 - Monterotondo Stazione (RM), Italy
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********************************************************
- Article premier - Les hommes naissent et demeurent
libres et égaux en droits. Les distinctions sociales
ne peuvent être fondées que sur l'utilité commune
- Article 2 - Le but de toute association politique
est la conservation des droits naturels et 
imprescriptibles de l'homme. Ces droits sont la liberté,
la propriété, la sûreté et la résistance à l'oppression.
********************************************************

   Giuseppe Mattioli                            
   CNR - ISTITUTO DI STRUTTURA DELLA MATERIA   
   v. Salaria Km 29,300 - C.P. 10                
   I 00015 - Monterotondo Stazione (RM), Italy    
   Tel + 39 06 90672836 - Fax +39 06 90672316    
   E-mail: <giuseppe.mattioli at ism.cnr.it>
   http://www.ism.cnr.it/english/staff/mattiolig
   ResearcherID: F-6308-2012