How to optimized a metal organic framework with a large ligand?

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1:41:20 PM PDT - Sat, Jun 18th 2016

Hello!

I am tryingg to optimize a metal organic framework with a large ligand.
I am unable to do so.
My input file is as follows.

restart MOF_bmbi
title "MOF_bmbi dft basis set"

charge 0

Geometry
end

basis

   C library  6-31G*

   H library  6-31G*

   N library  6-31G*

   Cu library 6-31G

   I library  3-21G

end

dft

   direct

   xc b3lyp

    iterations 100

    convergence energy 1e-3

   grid coarse

   TOLERANCES tol_rho 1e-7

end

task dft optimize

How can I improve my input file so that the huge MOF with 228 atoms can be optimized.