calculations not reaching convergence criteria


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Fragment Guess
Velyana
A good solution to your convergence problem is to use the Fragment Guess described in the NWChem manual at
http://nwchemgit.github.io/index.php/Hartree_Fock_Theory#Superposition_of_fragment_molecular...

Please have a look at the modified input file at the end of this posting.
In order to write this, I simply had to look at your molecular structure in a molecule viewer, identify the fragments,
then use a bit of intuition and use a trial and error approach to identify charge and multiplicity for each fragment.
Cheers, Edo
start cuglisin

echo
title "cuglisin"

charge 2

geometry big
 C                    0.28945382     2.81607562    -0.35707429
 O                   0.44365020     3.97345300    -0.87998681
 N                   -1.21118910     1.27281318     1.24447189
 C                   -1.15423910     2.61914048     0.62344566
 H                  -0.65306174     3.35065051     1.30884516
 H                  -2.40382216     1.99727708     1.75541574
 H                  -1.97085841     2.65259489    -0.20047399
Cu                   0.05199018    -0.06753972     0.09488464
 O                    1.31792913     1.42309499    -0.72998685
 O                   -1.11389771    -1.39465845    -0.90902526
 C                   -0.24533519    -2.54642195    -0.46429929
 N                    1.29617602    -1.48664811     0.97204001
 C                    0.86532236    -2.89659824     0.59375065
 H                   0.17100643    -3.39801344     1.74937774
 H                   1.91455851    -3.23352559     0.20426345
 O                  -0.66785734    -3.54112174    -0.91985462
 H                   2.46974811    -1.55280481     2.05122593
end
geometry co
 C                    0.28945382     2.81607562    -0.35707429
 O                   0.44365020     3.97345300    -0.87998681
end 
geometry cug1
 N                   -1.21118910     1.27281318     1.24447189
 C                   -1.15423910     2.61914048     0.62344566
 H                  -0.65306174     3.35065051     1.30884516
 H                  -2.40382216     1.99727708     1.75541574
 H                  -1.97085841     2.65259489    -0.20047399
end
geometry cucu
Cu                   0.05199018    -0.06753972     0.09488464
end
geometry cug2
 O                    1.31792913     1.42309499    -0.72998685
 O                   -1.11389771    -1.39465845    -0.90902526
 C                   -0.24533519    -2.54642195    -0.46429929
 N                    1.29617602    -1.48664811     0.97204001
 C                    0.86532236    -2.89659824     0.59375065
 H                   0.17100643    -3.39801344     1.74937774
 H                   1.91455851    -3.23352559     0.20426345
 O                  -0.66785734    -3.54112174    -0.91985462
 H                   2.46974811    -1.55280481     2.05122593
end
basis
 *   library 6-31G
end

driver
maxiter 200
end

charge 0
set geometry co
scf
 uhf
 singlet
 vectors input atomic output co.mos
end
task scf ignore

charge 0
set geometry cug1
scf
 uhf
 singlet
 vectors input atomic output cug1.mos
end
task scf ignore

charge -2
set geometry cug2
scf
 print mulliken
 uhf
 singlet
 vectors input atomic output cug2.mos
end
task scf ignore

set geometry cucu
charge 0
 scf
 doublet 
 vectors input atomic output cucu.mos
end

task scf

charge -2
set geometry big
scf
 uhf
 doublet 
 vectors input fragment co.mos cug1.mos cucu.mos cug2.mos output cug.mos
 maxiter 65
end
task scf