How can I get the final optimized coordinate PDB file after molecular mechanics optimization?

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6:57:59 AM PDT - Tue, Aug 28th 2012

After molecular mechanics optimization, I could not get optimized coordinate PDB file. The "1IVD_opt_final_1.pdb" was the same as the "1IVD_opt.pdb" file. How can I get the final optimized coordinate PDB file?

The prepare file is as follow:

start 1IVD

permanent_dir ./perm
scratch_dir ./data

prepare
system 1IVD_opt
source 6.pdb
periodic
new_top new_seq
new_rst
center
orient
solvate box 8.0
modify segment 471 quantum
update lists
ignore
write 1IVD_opt.pdb
write 1IVD_opt.rst
end

task prepare

The MM optimization input file is as follow:

echo

start 1IVD

memory total 25000 Mb
permanent_dir ./perm
scratch_dir ./data

prepare

read 1IVD_opt.rst

write 1IVD_opt_mm_1.rst

end

task prepare

md

system 1IVD_opt

sd 2000 init 0.01 min 1.0e-5 max 0.05

noshake solute

msa 6000

record rest 1

record coord 1

print step 1 extra

print energies 1

end

task md optimize

prepare

read 1IVD_opt.rst

write 1IVD_opt_final_1.pdb

end

task prepare