Re: [FreeON-devel] The FreeON wiki is open for business!

[Matt Challacombe]

Hi Gao,

There are examples in the freeon/Validate directory.  For the static
response there is the
file: Validate/Response/Static/Peroxide.inp    Note that only the HF
model has been implemented
so far, and for static response, only for polarization.  Also, the
polarization will not work
properly if the chosen axis is periodic, because it is gamma-point
only  (you can do z axis
polarization in a 2D slab though, with slab along xy plane).

There is also a TDSCF directory next door to static with the file:
Validate/Response/TDSCF/C2H4.inp  Again, this is only HF (RPA), but
you can do 1000's of atoms if you like.  The ref paper for dynamic
response is here: http://arxiv.org/pdf/1001.2586  I can get you the papers
for static response too.  This method also works very well, ie if you have
a local excitation, like a chromophore in a protein matrix.  Then, the cost
of RPA is O(1) while cost of SCF is O(N).

I think the question for you is, will TD-HF (RPA) be enough or do you need
a DFT component?  I'm pretty sure this is the only O(N) method for TD-SCF,
so it might be worth thinking about trying to implement the DFT part.
Programming
it is a bit time consuming, and I didn't have the time to do it yet.
Maybe you can live
without it though, or maybe you or someone you know is interested in
programming it a bit (I'd be willing to help but couldnt do it all).
Also, if you need
more than the first eigenvalue, you would need to do some extra programming.
I have that working somewhere in a prototype, but not strongly implemented.

I hope that helps.

Best, Matt

On Thu, Apr 26, 2012 at 3:58 PM, Gao Bin <address@hidden> wrote:
> Hi, Nick
>
> Thank you. Since I just started to use FreeON (indeed I am still struggling
> to get it be compiled), I am afraid I could not contribute immediately, but
> I will do my best :-)
>
> Now, I am trying to use FreeON. To me, the first step is to understand the
> keywords. I notice all the keywords are parsed in subroutines of FreeON
> directory, but there are ParseXX.f90 and XXKeys.f90. I wonder which files I
> should look into? Thank you so much.
>
> Another question is related to the feature mentioned in wiki page "Advanced
> features include O(N) static and dynamic response, as well as time
> reversible Born Oppenheimer Molecular Dynamics (MD)". I am interested in
> dynamic response, but I did not find any routine in FreeON/Response.f90
> related to dynamic response. Did I misunderstand or did I look into a wrong
> file? Moreover, may I ask what the reference papers for static and dynamic
> response? I notice there are some reference papers in
> http://en.wikipedia.org/wiki/FreeON, but I am not sure which one and if they
> are enough. Therefore, I think it would be better to put the reference list
> in the current wiki page (well, just my opinion).
>
> Cheers
>
> Gao
> ________________________________
> From: Nicolas Bock address@hidden
> Sent: Wednesday, April 25, 2012 8:40 PM
> To: address@hidden; freeon-devel; Gao Bin; Jose R. Valverde
> Subject: The FreeON wiki is open for business!
>
> Hi,
>
> please visit
>
> http://freeon.lanl.gov
>
> and check out our new wiki. There is nothing really on there yet, but we are
> hoping that with your help there will be soon. The wiki is completely open,
> which means that you can add, edit, and delete content as you wish, with or
> without a wiki account.
>
> I suggest we think about what information a user or a developer would like
> to find on a wiki. My guess is (in no particular order of importance):
>
> * API
> * Input file syntax
> * Example inputs, illustrating all features of FreeON
> * A feature list
>
> I would like to encourage you to add to this list and of course to start
> adding content to the wiki.
>
> Thanks already for your help,
>
> nick
>
>
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