geometry optimization - Load of old vectors failed

From NWChem

Viewed 615 times, With a total of 2 Posts
Jump to: navigation, search

Clicked A Few Times
Threads 5
Posts 10
Dear all,
I'm doing geometry optimization of 46 atoms molecule in two steps - at first I do it with small basis set (3-21G) and then I proceed to larger one (6-31+G*). The problem I'm facing is that for the larger basis set I'm getting "Load of old vectors failed. Forcing atomic density guess" error for each GO step. My input is following:

start dimerBO4-MM1c2_GO-B3LYP-631+Gstar

MEMORY stack 5200 heap 1000 global 1600 mb
title "beta-O4-dimer in ccl4, initial structure from oBabel weighted conf search (MM1) - c2, geometry optimization B3LYP 6-31+G*"

geometry units an print xyz noautosym noautoz
 H     2.74728191    -1.87018077     0.49356313
 C     1.72555291    -1.97047424     0.15863115
 C     1.12899352    -3.24218872     0.17964039
 O     1.96933124    -4.25797191     0.60162743
 C    -0.19656223    -3.38790055    -0.24929258
 O    -0.79192717    -4.65958655    -0.30669082
 C    -0.91324611    -2.24393212    -0.67249208
 O    -2.22077430    -2.48421901    -1.08008852
 C    -0.31411507    -0.98971986    -0.67583103
 H    -0.86583681    -0.10748981    -0.96093248
 C     1.01908701    -0.85750889    -0.26635916
 C     1.69478932     0.50210090    -0.26732380
 C     1.22178953     1.37964278     0.89640709
 H     1.34188160     0.84978156     1.84355039
 O    -0.22475252     1.64120707     0.71069941
 H     1.79480222     2.30647875     0.89961233
 C    -0.65466895     2.96150475     0.56918867
 C    -0.10474974     3.85199495    -0.38003637
 O     0.94030871     3.35659764    -1.15210260
 C    -0.62972838     5.13932065    -0.49507947
 H    -0.21664636     5.82929823    -1.21832745
 C    -1.69899429     5.54906150     0.30861234
 H    -2.09428614     6.55189615     0.19986531
 C    -2.24828452     4.66929881     1.23895458
 H    -3.07503245     4.97682120     1.86749103
 C    -1.71336063     3.38480684     1.36765346
 H    -2.11074093     2.67964948     2.08652543
 C    -3.00477286    -1.34005795    -1.55237925
 C    -1.95620029    -4.84465172     0.59664725
 C     1.44330427    -5.55509670     1.05471651
 H     0.98066598    -6.10689918     0.23912070
 H     0.71601445    -5.42796803     1.86326679
 H     2.32230566    -6.08044581     1.43156313
 H    -2.73451143    -4.12344464     0.35070904
 H    -1.65328033    -4.73886515     1.64432851
 H    -2.30053072    -5.86292824     0.40972777
 H    -3.13695738    -0.59222366    -0.76298002
 H    -3.97084098    -1.75979957    -1.83304676
 H    -2.53541718    -0.86941768    -2.42299522
 C     1.56208176     4.25650905    -2.12795948
 H     1.99236445     5.13724910    -1.63921061
 H     0.84135268     4.57615503    -2.88859268
 H     2.35177257     3.66495837    -2.59038307
 O     3.13735166     0.39463213    -0.05091155
 H     3.51914450    -0.06909010    -0.84439266
 H     1.45671359     1.04924943    -1.18524217
end

#basis small
# * library 3-21G
#end

basis
 * library 6-31+G*
end

#set "ao basis" large


dft
  xc b3lyp
  CONVERGENCE density 1e-8
  CONVERGENCE energy 1e-8
  GRID lebedev 90 14 ssf euler
  MAXITER 60
  semidirect filesize 5000000 memsize 200000000 
end

driver
 EPREC 1e-8
 GRMS 0.000004
 MAXITER 900
 XYZ geomSteps
end

task dft optimize



and here is the corresponding part of the output:

 WARNING : Found     9 linear dependencies 
 S eigenvalue threshold:     1.00000E-05
 Smallest S eigenvalue :     3.82890E-07
 Largest  S eigenvalue :     9.55154E-06
 

 !! The overlap matrix has   9 vectors deemed linearly dependent with
    eigenvalues:
 3.83D-07 1.03D-06 2.05D-06 2.71D-06 3.60D-06 4.79D-06 6.20D-06 8.02D-06
 9.55D-06
 

 !! nbf/nmo/basis-name mismatch 
           nbf= 500 nbf_file= 500
           nmo= 491 nmo_file= 490
           basis="ao basis" basis_file="ao basis"

  Either an incorrect movecs file was 
 specified, or linear dependence has changed,
  or the basis name was changed. 

 Loading old vectors from job with title :

beta-O4-dimer in ccl4, initial structure from oBabel weighted conf search (MM1) - c2, geometry optimization B3LYP 6-31+G*

 
  Load of old vectors failed.   Forcing atomic density guess



I also tried restarting the calculation from the previous optimization in smaller basis set projecting to larger basis with the same result.
Do you have anybody idea why is this happening?
thank you
stanislav.

Gets Around
Threads 1
Posts 147
Most likely the number of linearly dependent vectors is changing from one step to the next as the geometry changes. Essentially this means that the size of your basis set changes from one step to the next, so the code disregards the old vectors and starts the SCF for the current step from scratch. You can just leave it alone and it will continue on just fine, albeit a little slower since it is starting from scratch rather than using the previous step as a guess for the current step. Alternatively you can add

set lindep:n_dep n

to your input, where n is an integer that forces the code to always consider n vectors as linearly dependent. With this setting, the code will always be able to use the previous set of vectors as a guess for the current step since you have fixed the size of the basis. You just need to be cautious of numerical stability problems if you set n too small and include vectors that are (nearly) linearly dependent in your SCF calculation.

Clicked A Few Times
Threads 5
Posts 10
Thank you. Also, other calculations (other conformers) are doing better.


Forum >> NWChem's corner >> Running NWChem



Who's here now Members 0 Guests 0 Bots/Crawler 1


AWC's: 2.5.10 MediaWiki - Stand Alone Forum Extension
Forum theme style by: AWC