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Re: [FreeON-devel] problem of compiling Modules/LinAlg.F90 using mpif90

From: Matt Challacombe
Subject: Re: [FreeON-devel] problem of compiling Modules/LinAlg.F90 using mpif90 (backend compiler ifort)
Date: Sun, 27 May 2012 17:31:08 -0600

> But I did not find any openmp directive in the source codes. What should I do 
> to use FreeON, let us say, in a node with 8 CPUs using openmp?

Currently, that code is not available to you (its in beta, and just
for the linear algebra: SpAMMPack).  If it turns out you really want
we could prob get it going in a couple days with modest efficiency.
If the rest of your project with FreeON looks viable, I'd be willing
to try and
get that working for/with you.

> My code could read HDF5 file, so it would be better that I could have the 
> atomic orbital density matrix and Fock matrix in a HDF5 file after SCF 
> calculations. Should I modify the code?

If your code reads a dense matrix, you can use SetEq to convert from
BCSR to DBL_RNK2, and put the RNK2 into the HDF (or whatever).
Alternatively, you can put the BCSR to disk, and take the BCSR
formatted read code from InOut (thats probably easier).   In either
case,  the AO density matrix is available after
RHeqs or SP2 is run.  The AO Fock matrix should be available after
FockBuild is run.  If its not lableled "ortho" its probably "AO".
Turning "MaxDebug" in
your input file should give you the subprograms invocation in your run.

> I only need SCF calculations, and will probably require 5-6 digits. The 
> molecule is like protein, so the band gap should be OK. Our computer clusters 
> here either have 8 CPUs or 12 CPUs per node (around 2.7 GHz), with 16GB or 24 
> GB memory. May I ask, from your experience, how long a calculation of 3-4K 
> atoms with 6-31G will take on this machine? Thank you.

5-6 digits is somewhere between our thresholds "Loose"  (4-5) and
"Good" (6-7).  I'd try first with "Loose" accuracy in your preliminary
I think 24GB may be too small for 3-4K atoms.  You will probably have
to experiment to see how big you can go.  The matrix allocation is I
believe wired to allocate full (N^2) matrices,
for generality.  We can talk about a more agressive O(N) allocation
scheme (its in the code, just needs activation) that will require a
little experimentation
to get right for your specific case.  I'll show you when time comes.
This is a bit of a pain, and one reason we are re-writing the linear
algebra from ground up (again).

>          20           0           0           3
> which look like FreeON starts from xxx to the yyy corner, and then xxz down 
> to yyz, and finally the zzz corner. This is great, since my code uses the 
> same indexing.

Yeah, I'm pretty sure thats (close to) standard. I'm not sure
F-functions are "on" everywhere in your version.  I think there are a
couple mods I will
have to make in QCTC to turn them back on.  I need to do it anyway for
my research goals.  Let me know if you need them before I get to it.

As you can see, its an experimental code.  We'd like to make it less
experimental for users -- so as you run into problems, I'll try to
harden some of the features.


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