Convergence problem...

Clicked A Few Times

2:09:22 PM PST - Tue, Jan 21st 2014

Hi, I'm having trouble getting optimizing a system..
It gives the error as

dft optimize failed                                                                     0

------------------------------------------------------------------------

This type of error is most commonly associated with calculations not reaching convergence criteria

This is the inout (.nw) file I'm using ..

start ho_hocl

geometry units angstroms

O                  0.33520249    2.39077715   -0.00683931

H                 -0.37981087    0.74868511    0.17285391

O                 -0.82593007   -0.08154900   -0.00959877

Cl                 0.27430978   -1.31115211   -0.00263665

H                  1.29229047    2.31606903   -0.00797856

end

basis

library 6-311++G**

end

dft

mult 2

xc m06-2x

iterations 2000000000000

end

task dft optimize
task dft freq

Hope someone can help me with this.
Thanks a lot.

Forum Vet

6:41:36 PM PST - Tue, Jan 21st 2014

Mhiranya,
A way to converge this input is by first converging a HF calculation, then using the HF Molecular Orbital to start
the m06-2x calculation.
The input below implement this methods.
Cheers, Edo

start ho_hocl

geometry units angstroms
O                  0.33520249    2.39077715   -0.00683931
H                 -0.37981087    0.74868511    0.17285391
O                 -0.82593007   -0.08154900   -0.00959877
Cl                 0.27430978   -1.31115211   -0.00263665
H                  1.29229047    2.31606903   -0.00797856

end

basis
 *  library 6-311++G**
end

dft
mult 2
xc hfexch
vectors input atomic output hf.mos
end
task dft

dft
xc m06-2x
grid fine
vectors input hf.mos output m062x.mos
end

task dft

Clicked A Few Times

3:41:27 PM PST - Wed, Jan 22nd 2014
Edo, I tried the input you gave but still I'm getting error saying the optimization failed and calculations not reaching the convergence criteria. Thanks

Forum Vet

9:53:35 AM PST - Thu, Jan 23rd 2014
Mhiranya Please post or upload the full output/error file. Thanks

Clicked A Few Times

7:07:17 PM PST - Thu, Jan 23rd 2014

here it is... hope you can help me with this.. Thanks

   3 O                |   2 H                |     1.83455  |     0.97080

   4 Cl               |   3 O                |     3.20503  |     1.69603

   5 H                |   1 O                |     1.84364  |     0.97561

------------------------------------------------------------------------------

                        number of included internuclear distances:          3

==============================================================================

==============================================================================
                                internuclear angles

------------------------------------------------------------------------------

       center 1       |       center 2       |       center 3       |  degrees

------------------------------------------------------------------------------

   2 H                |   3 O                |   4 Cl               |   102.39

------------------------------------------------------------------------------

                           number of included internuclear angles:          1

==============================================================================

------------------------------------------------------------------------

dft optimize failed                                                                     0

------------------------------------------------------------------------

This type of error is most commonly associated with calculations not reaching convergence criteria

------------------------------------------------------------------------

For more information see the NWChem manual at http://nwchemgit.github.io/index.php/NWChem_Documentation

For further details see manual section:

Forum Vet

7:21:59 PM PST - Thu, Jan 23rd 2014
OK, This is not the full output file, but it's probably enough. The geometry optimization is now running out of geometry steps (from the default 20). In other words, your run has computed 20 energy points, but the minimum has not been reached yet. To fix this, please add the following to your input file. driver maxiter 99 end task dft optimize task dft freq

Clicked A Few Times

9:49:14 PM PST - Thu, Jan 23rd 2014
It worked. Thank you very much Edoapra. By the way so can we change the '99' to some other number (greater than 20) ??

Clicked A Few Times

9:50:34 PM PST - Thu, Jan 23rd 2014
one more thing, Is there a way to get partial charges of each atom .. Thanks a lot.

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