Linear Dependencies

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Hey All,

I'm new to computational chemistry in general, and NWChem in particular, so I would really appreciate any help/explanation with this error and how to proceed! I've posted the input and excerpts from the output file. I killed the job before it finished because I've been having this problem consistently.

Input:
echo

start molecule

title "imide"
charge 0

geometry units angstroms print xyz autosym noautoz
C           1.599748   -0.446301   -0.001404
C 0.720226 0.632008 -0.007068
C -0.720251 0.631984 -0.006908
C -1.599736 -0.446351 -0.000700
C 1.307492 -1.893255 0.005910
C -1.307434 -1.893291 0.007268
N 0.000037 -2.380608 0.009392
C 2.972337 -0.044555 -0.003498
C 3.137575 1.305552 -0.010945
S 1.616880 2.138796 -0.015252
C -2.972340 -0.044652 -0.002928
C -3.137623 1.305446 -0.010823
S -1.616957 2.138743 -0.014893
H 3.776811 -0.767511 0.000378
H 4.058488 1.871243 -0.014193
H -3.776789 -0.767634 0.001190
H -4.058556 1.871105 -0.014231
O 2.217089 -2.714440 0.010880
H 0.000055 -3.396828 0.014434
O -2.217004 -2.714512 0.011160
end

basis spherical
 * library aug-cc-PVDZ
end

dft
xc xbnl07 0.90 lyp 1.00 hfexch 1.00
cam 0.250000 cam_alpha 0.0 cam_beta 1.0
direct
iterations 500
end

task dft energy



Excerpts from output:

"WARNING : Found 7 linear dependencies
S eigenvalue threshold:     1.00000E-05
Smallest S eigenvalue : 2.26478E-06
Largest S eigenvalue : 7.40825E-06


!! The overlap matrix has   7 vectors deemed linearly dependent with
eigenvalues:
2.26D-06 2.90D-06 4.85D-06 5.08D-06 6.87D-06 6.92D-06 7.41D-06"

"WARNING: error on integrated density = 0.24D-03
greater than required accuracy of  0.10D-05"

Thank you!

  • Bert Forum:Admin, Forum:Mod, NWChemDeveloper, bureaucrat, sysop
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That NWChem found linear dependencies is perfectly normal. They are removed from the calculation to provide better convergence.

Being off in the integrated density suggests a not so good starting guess. This should get better once 1) DFT gets closer to convergence, and 2) when DFT optimize gets closer to the real optimal geometry.

Bert



Quote:Roo464 Mar 29th 7:14 pm
Hey All,

I'm new to computational chemistry in general, and NWChem in particular, so I would really appreciate any help/explanation with this error and how to proceed! I've posted the input and excerpts from the output file. I killed the job before it finished because I've been having this problem consistently.

Input:
echo

start molecule

title "imide"
charge 0

geometry units angstroms print xyz autosym noautoz
C           1.599748   -0.446301   -0.001404
C 0.720226 0.632008 -0.007068
C -0.720251 0.631984 -0.006908
C -1.599736 -0.446351 -0.000700
C 1.307492 -1.893255 0.005910
C -1.307434 -1.893291 0.007268
N 0.000037 -2.380608 0.009392
C 2.972337 -0.044555 -0.003498
C 3.137575 1.305552 -0.010945
S 1.616880 2.138796 -0.015252
C -2.972340 -0.044652 -0.002928
C -3.137623 1.305446 -0.010823
S -1.616957 2.138743 -0.014893
H 3.776811 -0.767511 0.000378
H 4.058488 1.871243 -0.014193
H -3.776789 -0.767634 0.001190
H -4.058556 1.871105 -0.014231
O 2.217089 -2.714440 0.010880
H 0.000055 -3.396828 0.014434
O -2.217004 -2.714512 0.011160
end

basis spherical
 * library aug-cc-PVDZ
end

dft
xc xbnl07 0.90 lyp 1.00 hfexch 1.00
cam 0.250000 cam_alpha 0.0 cam_beta 1.0
direct
iterations 500
end

task dft energy



Excerpts from output:

"WARNING : Found 7 linear dependencies
S eigenvalue threshold:     1.00000E-05
Smallest S eigenvalue : 2.26478E-06
Largest S eigenvalue : 7.40825E-06


!! The overlap matrix has   7 vectors deemed linearly dependent with
eigenvalues:
2.26D-06 2.90D-06 4.85D-06 5.08D-06 6.87D-06 6.92D-06 7.41D-06"

"WARNING: error on integrated density = 0.24D-03
greater than required accuracy of  0.10D-05"

Thank you!


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