There is something happening about this calculation with NWCHEM6.8 on macOS High Sierra with GCC 7.2.0, mpich 3.2.1 and Xcode 9.2.
First, the calculation using aug-cc-pvtz could not converge
...
Entering Davidson iterations
Unrestricted
Iter NTrls NConv DeltaV DeltaE Time
---- ------ ------ --------- --------- ---------
1 10 0 0.15E+00 0.10+100 328.3
------------------------------------------------------------------------
tddft_diagon: negative excitation energy 0
------------------------------------------------------------------------.
Second, the one with aug-cc-pvdz was successful for one time
...
Root 1 a 0.000479490 a.u. 0.0130 eV
<S2> = 0.9633
----------------------------------------------------------------------------,
...
----------------------------------------------------------------------------
Root 2 a 0.000721485 a.u. 0.0196 eV
<S2> = 0.9615
----------------------------------------------------------------------------
...
----------------------------------------------------------------------------
Root 3 a 0.001720248 a.u. 0.0468 eV
<S2> = 0.8747
----------------------------------------------------------------------------
...
Root 4 a 0.010212053 a.u. 0.2779 eV
<S2> = 0.7555
----------------------------------------------------------------------------
...
but failed when the computer was restarted using the same input
...Entering Davidson iterations
Unrestricted
Iter NTrls NConv DeltaV DeltaE Time
---- ------ ------ --------- --------- ---------
1 10 0 0.15E+00 0.10+100 151.3
2 30 0 0.79E-01 0.35E-01 205.2
------------------------------------------------------------------------
tddft_diagon: negative excitation energy 0
------------------------------------------------------------------------
------------------------------------------------------------------------
current input line :
29: task tddft energy
------------------------------------------------------------------------
...
Finally, the repeated CIS TDDFT calculations had a small difference with aug-cc-pvdz:
1. ...
Root 1 a 0.008091830 a.u. 0.2202 eV
<S2> = 0.9172
----------------------------------------------------------------------------
...
----------------------------------------------------------------------------
Root 2 a 0.008125684 a.u. 0.2211 eV
<S2> = 0.9172
----------------------------------------------------------------------------
...
2. ...
Root 1 a 0.008077333 a.u. 0.2198 eV
<S2> = 0.9181
----------------------------------------------------------------------------
...
Root 2 a 0.008115493 a.u. 0.2208 eV
<S2> = 0.9181
----------------------------------------------------------------------------
...
GAMESS gave 0.048eV, 0.048eV and 0.284eV,which could be reproduced from different versions.
Do these mean the rohf calculation using NWCHEM was very unstable in this case and a patch is required?
Thanks a lot.
Very Best regards!
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