Skip to first unread message
Mariana H
Nov 23, 2021, 8:03:37 AM11/23/21
to nwchem...@googlegroups.com
Dear all,
I have a question regarding a frequency calculation in NwChem. I optimised a Cl-BsubPc molecule and reached a minimum that also agrees well with experimental data. However, when running a frequency calculation, I obtain three negative frequencies:
----------------------------------------------------------------------------
Normal Eigenvalue || Projected Infra Red Intensities
Mode [cm**-1] || [atomic units] [(debye/angs)**2] [(KM/mol)] [arbitrary]
------ ---------- || -------------- ----------------- ---------- -----------
1 -199.878 || 0.000773 0.018 0.753 0.426
2 -199.855 || 0.000774 0.018 0.755 0.427
3 -90.562 || 0.003152 0.073 3.072 1.738
4 -0.000 || 0.000000 0.000 0.000 0.000
5 -0.000 || 0.000259 0.006 0.252 0.143
6 -0.000 || 0.000008 0.000 0.007 0.004
7 -0.000 || 0.000266 0.006 0.259 0.147
8 -0.000 || 0.000000 0.000 0.000 0.000
9 0.000 || 0.000002 0.000 0.002 0.001
10 75.295 || 0.000294 0.007 0.287 0.162
11 75.341 || 0.000296 0.007 0.289 0.163
12 127.092 || 0.000000 0.000 0.000 0.000
13 137.566 || 0.001530 0.035 1.491 0.843
14 137.581 || 0.001526 0.035 1.488 0.841
15 161.465 || 0.002184 0.050 2.129 1.204
16 161.490 || 0.002186 0.050 2.131 1.205
17 192.422 || 0.000405 0.009 0.395 0.223
18 231.180 || 0.000000 0.000 0.000 0.000
19 250.919 || 0.002884 0.067 2.811 1.590
20 250.921 || 0.002891 0.067 2.818 1.594
21 296.542 || 0.008318 0.192 8.109 4.586
22 321.871 || 0.003929 0.091 3.830 2.166
23 321.919 || 0.003936 0.091 3.837 2.170
24 337.794 || 0.000111 0.003 0.108 0.061
25 337.916 || 0.000097 0.002 0.094 0.053
26 346.734 || 0.000904 0.021 0.882 0.499
27 410.295 || 0.019077 0.440 18.597 10.518
28 432.464 || 0.000000 0.000 0.000 0.000
29 442.411 || 0.000014 0.000 0.013 0.007
30 442.420 || 0.000015 0.000 0.014 0.008
31 451.111 || 0.019219 0.443 18.735 10.596
32 513.228 || 0.000322 0.007 0.314 0.178
33 513.255 || 0.000324 0.007 0.315 0.178
34 526.748 || 0.004802 0.111 4.682 2.648
35 526.799 || 0.004785 0.110 4.664 2.638
36 580.695 || 0.000000 0.000 0.000 0.000
37 581.901 || 0.013502 0.312 13.163 7.444
38 581.909 || 0.013513 0.312 13.173 7.450
39 629.555 || 0.000000 0.000 0.000 0.000
40 641.855 || 0.001187 0.027 1.157 0.654
41 641.859 || 0.001195 0.028 1.165 0.659
42 649.522 || 0.021861 0.504 21.311 12.052
43 653.732 || 0.000000 0.000 0.000 0.000
44 664.975 || 0.003004 0.069 2.929 1.656
45 664.981 || 0.003010 0.069 2.935 1.660
46 720.941 || 0.000717 0.017 0.699 0.395
47 730.957 || 0.006835 0.158 6.663 3.768
48 730.961 || 0.006774 0.156 6.604 3.735
49 746.408 || 0.018805 0.434 18.332 10.368
I tried switching to task dft freq numerical and to increase the grid size to huge, however so far I could not solve the problem. Also, I tried switching from the diffuse aug-cc-pvtz basis set I was previously using to a more simple basis set in order to see if it has any influence, but that does not seem to be the case.
This is my latest input file:
echo
start CO+_PBE
title CO+_PBE
geometry units angstroms noautosym
C 0.93520996 -3.19627517 -0.20235192
C -0.05351249 -2.27523883 0.32130452
N 0.64990810 -1.18986760 0.73467027
C 1.94297049 -1.18545320 0.32006234
C 2.18231520 -2.51549043 -0.20322501
C -3.27007016 -0.63247187 -0.19836462
C -3.23616185 0.78791571 -0.19809140
C -1.94350674 1.18390356 0.32382568
N -1.35498553 0.03222664 0.73774365
C -1.99783321 -1.08989776 0.32350637
N 0.70599042 1.15713852 0.73488141
C 0.05523335 2.27505238 0.32201490
C 1.08684097 3.14797977 -0.20128025
C 2.30001979 2.40841285 -0.20235705
C 1.99740518 1.09112240 0.32041675
C 3.31573007 -3.11746282 -0.73402408
C 3.19953158 -4.40219792 -1.23215501
C 1.97097088 -5.07298464 -1.23107392
C 0.82806143 -4.47564796 -0.73195973
C 1.04096809 4.43128281 -0.73021819
C 2.21114614 4.97356816 -1.22902026
C 3.40627999 4.24487276 -1.23031662
C 3.46096664 2.95585238 -0.73270690
C -4.35850076 -1.31332247 -0.72797847
C -5.41349760 -0.57056459 -1.22546843
C -5.38011116 0.82877726 -1.22515115
C -4.29085891 1.52014751 -0.72740420
B 0.00112769 -0.00025285 1.33531178
N 2.64848558 -0.06337965 0.19035494
N -1.26947462 2.32508432 0.19388921
N -1.37906909 -2.26192680 0.19320027
Cl 0.00380704 -0.00038428 3.19261564
H 4.26147442 -2.59102208 -0.74956964
H 4.07290077 -4.89981566 -1.63552740
H 1.91680063 -6.07703802 -1.63362334
H -0.12616350 -4.98659053 -0.74582592
H 0.11225654 4.98727842 -0.74385972
H 2.20503185 5.97927495 -1.63106530
H 4.30246133 4.70043330 -1.63337209
H 4.38048412 2.38481931 -0.74843170
H -4.37550077 -2.39558070 -0.74289388
H -6.28149401 -1.07831306 -1.62780926
H -6.22290307 1.37753428 -1.62723412
H -4.25622454 2.60199531 -0.74185603
end
BASIS PRINT
* library 6-31g
end
dft
direct
vectors output CO+.movecs
xc pbe0
convergence diis 5
grid huge
convergence energy 1e-8
convergence gradient 1e-6
convergence density 1e-6
iterations 300
end
task dft energy
freq
reuse
end
task dft freq numerical
Could you please advise me on this?
Best wishes, Mariana.
Edoardo Aprà
Nov 23, 2021, 7:18:07 PM11/23/21
to NWChem Forum
This is slightly modified input that will give you zero negative frequencies
echo
start CO+_PBE
title CO+_PBE
start CO+_PBE
title CO+_PBE
memory total 2000 mb noverify
geometry units angstroms# noautosym
geometry units angstroms# noautosym
BASIS spherical PRINT
* library 6-31g
end
dft
sym off
adapt off
direct
xc pbe0
tolerances acccoul 13
grid fine
end
driver
tight
clear
end
task dft energy optimize
dft
grid huge
end
task dft freq
adapt off
direct
xc pbe0
tolerances acccoul 13
grid fine
end
driver
tight
clear
end
task dft energy optimize
dft
grid huge
end
task dft freq
Reply all
Reply to author
Forward
0 new messages