Re: CCL:Computation Resource Requirement.

[Kadir Diri <kadir~at~visual1.chem.pitt.edu>]

 Hi! What you can do to get an idea about the timings on a single cpu is
 the following: do a smaller calculation (smaller basis set and/or
 smaller molecule). Then scale the timings accordingly for larger basis
 sets and more atoms. In Hartree-Fock, the 2 electron integrals will
 scale as N^4 but the integral transformation will scale as N^5.
 As to the case with multiple CPU`s, it depends on many factors, for
 example on how good the code that you use is. Also, the speed will vary
> from one architecture to another. It is also important
>  how the code
>  
works, i.e. whether it uses shared memory on a multiple
 cpu machine or
 whether it runs across many nodes. There are probably many other
 factors, like the speed and the configuration of the network, so it is
 not very easy to answer that part of your question, but you will be
 able
 to figure out the answer after a few test calculations.
 kadir
 Pijush Ghosh wrote:
>  CCL Users,
>       being new to the field of computational quantum mechanics, i
>  have a basic question on the requirement of the resources for this
>  type of computation.  Can anybody  cite any reference where i can get
>  some relation between number of processors and time required  with
>  that of number of atoms in a system , basis set used, etc.
>      In my system of Hydroxyapatite- polymer I have the following details:
>  atom                 number
>  Calcium              20
>  Phosphorous      12
>  Oxygen              54
>  Hydrogen           10
>  Carbon                 3
>  Basis set -            6-31+G**
>  Method -              HF (Hartree Fock)
> can somebody  give idea on  processor-hour required. All my
>  simulations are run on NCSA machines.
>  All suggesions and information appreciated in advance.
>  Pijush Ghosh.
>  NDSU.
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