[Pw_forum] TDDFT approach for periodic system

[O. Baris Malcioglu]

A further addition and good reading why adding k-points to TDDFT might not
be that straightforward:

THE JOURNAL OF CHEMICAL PHYSICS 129, 034101
"Why are time-dependent density functional theory excitations in solids
equal to band structure energy gaps for semilocal functionals, and how does
nonlocal Hartree–Fock-type exchange introduce excitonic effects?"
Artur F. Izmaylov and Gustavo E. Scuseriaa

2011/4/20 O. Baris Malcioglu <baris.malcioglu at gmail.com>

> Dear All,
> The current implementation of TDDFPT in Q-E is intended for "standalone"
> systems (i.e. non bulk, solvated or encapsulated in dielectric systems are
> ok). You will see confinement effects in lower dimensional systems
> (including 1D and 2D systems) in the non-extended dimensionality(-ies) save
> excitations with strong Mott-Wannier like character (CT excitations in
> theoretical chemistry) since the oscillator strength for them in the current
> implementation goes to zero due to ALDA (working on that). For the extended
> dimensions you'll see no accountable difference from run-of-the-mill DFT-RPA
> save if there is an extraordinarily strongly bound exciton at gamma point
> (i.e. strongly ionic materials) (please see how TDDFT is formulated through
> response -charge-, and how K points may come into play). For "ordinary" bulk
> materials, frequency dependence and long range tail of the kernel is
> generally mandatory for a bound exciton, which is quite "tricky" to add I
> would say (beware of EXX and TD-HF, they tend to have quite wrong exciton
> binding energies, personally I think this is due to lack of inclusion of a
> proper generalised dielectric function in their formulation).  If you want
> to study "ordinary bulk materials" I would recommend you BSP or TD-CFT
> whenever GW can not save the day. Did you try SAX?
> Best,
> Baris
> P.S.
> (There are many books on the topic, especially regarding what to expect and
> what not to expect from TDDFT, my personal opinion is that TDDFT thrives in
> the realm between theoretical chemistry and bulk materials, i.e. large
> molecules, nanocrystals, etc. Then again, this is my personal opinion)
> I would recommend you to start with M.A.L. Marques, C.A. Ullrich, F.
> Nogueira, A. Rubio, K. Burke, and E.K.U. Gross (eds.), Time-Dependent
> Density Functional Theory (Springer-Verlag, 2006). )
>
> 2011/4/20 Giuseppe Mattioli <giuseppe.mattioli at mlib.ism.cnr.it>
>
>> Dear all
>> I did not say that TDDFPT does not work with periodic system, but you
>> cannot
>> have a realistic absorption spectra of a slab (or bulk crystal) if you
>> sample
>> the Brillouin zone by using Gamma only... TDDFPT works fine with finite
>> systems, i.e., which do not show a (strong) k dependence of the psi_n,k
>> eigenvalues.
>>
>> Giuseppe
>>
>> On Wednesday 20 April 2011 03:00:41 Johari, Priya Sudhir wrote:
>> > Thanks Marton, its working.
>> >
>> > On Tue, Apr 19, 2011 at 5:40 PM, Marci <vormar at gmail.com> wrote:
>> > > Dear Priya,
>> > >
>> > > Though I have never tried, it should work with periodic systems if you
>> > > sample the Brillouin zone only with the gamma point. Keep in mind that
>> > > the usual adiabatic approximations with (semi)local functionals might
>> > > not work very well for calculating the absorption of periodic systems.
>> > >
>> > > Marton
>> > >
>> > > --
>> > > Marton Voros
>> > > PhD student
>> > > Department of Atomic Physics
>> > > Budapest University of Technology and Economics
>> > > Budafoki út 8., H-1111, Budapest, Hungary
>> > > www.fat.bme.hu/MartonVoros
>> > >
>> > > On Tue, Apr 19, 2011 at 11:02 PM, Johari, Priya Sudhir
>> > >
>> > > <priya_johari at brown.edu> wrote:
>> > > > Thanks Duy, but the link does not give sufficient information.
>> However,
>> > > > I found a discussion on forum's archive itself where Giuseppe
>> Mattioli
>> > > > has mentioned that TDDPFT does not work for periodic systems :-(
>> > > >
>> > > > Dr Priya Johari.
>> > > > Brown University,
>> > > > Providence, RI - 02906. USA
>> > > >
>> > > > On Tue, Apr 19, 2011 at 3:59 PM, Duy Le <ttduyle at gmail.com> wrote:
>> > > >> If you do a little homework (such as googling keyword TD-DFPT),
>> you'll
>> > > >> find this link
>> > > >> http://qe-forge.org/projects/tddfpt/
>> > > >> I have not read it carefully but I guess it contains some useful
>> > > >> information.
>> > > >> --------------------------------------------------
>> > > >> Duy Le
>> > > >> PhD Student
>> > > >> Department of Physics
>> > > >> University of Central Florida.
>> > > >>
>> > > >> "Men don't need hand to do things"
>> > > >>
>> > > >>
>> > > >>
>> > > >> On Tue, Apr 19, 2011 at 3:26 PM, Johari, Priya Sudhir
>> > > >>
>> > > >> <priya_johari at brown.edu> wrote:
>> > > >> > TD-DFPT
>> > > >>
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>>
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>>    Giuseppe Mattioli
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