TURBOMOLE Users Forum
Installation and usage of TURBOMOLE => Sequential Runs => Topic started by: ComingNine on March 29, 2010, 05:53:02 PM
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Dear TURBOMOLE support, question about the converged energy,thank you very much!
Dear TURBOMOLE support,
Please have a look at the output of one ridft calculation of C2H5-OH
Starting SCF iterations
Overall gridpoints after grid construction = 3901
ITERATION ENERGY 1e-ENERGY 2e-ENERGY NORM[dD(SAO)] TOL
1 -115.62050121264 -236.25587770 80.640718764 0.000D+00 0.877D-09
Exc = -15.4761720067 Coul = 96.1168907710
N = 17.999727430
current damping = 0.700
max. resid. norm for Fia-block= 2.497D-05 for orbital 5a'
max. resid. fock norm = 8.537D-05 for orbital 21a'
ITERATION ENERGY 1e-ENERGY 2e-ENERGY NORM[dD(SAO)] TOL
2 -115.62050121553 -236.25604933 80.640890393 0.835D-04 0.556D-09
Exc = -15.4761923167 Coul = 96.1170827092
N = 17.999727416
current damping = 0.700
Norm of current diis error: 0.53008E-04
max. resid. norm for Fia-block= 1.111D-05 for orbital 6a'
max. resid. fock norm = 3.344D-05 for orbital 21a'
ENERGY CONVERGED !
Overall gridpoints after grid construction = 14447
ITERATION ENERGY 1e-ENERGY 2e-ENERGY NORM[dD(SAO)] TOL
3 -115.62066272068 -236.25591853 80.640598086 0.399D-04 0.461D-09
Exc = -15.4763379432 Coul = 96.1169360292
N = 17.999999749
current damping = 0.750
Norm of current diis error: 0.33078E-04
max. resid. norm for Fia-block= 4.671D-06 for orbital 5a'
max. resid. fock norm = 1.461D-05 for orbital 21a'
End of SCF iterations
convergence criteria satisfied after 3 iterations
...
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| total energy = -115.62066272068 |
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: kinetic energy = 114.60891611891 :
: potential energy = -230.22957883958 :
: virial theorem = 1.99124943087 :
: wavefunction norm = 1.00000000000 :
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I am wondering, after the line "ENERGY CONVERGED", why ridft will calculate again, and why there is a large difference between the values below and above the line "ENERGY CONVERGED"?
I mean, the "total energy = " value is not the actually converged values. Could you help to explain a little to me?
Thank you very much for your time and effort!
Best wishes,
Xichen
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Hi,
please note that this forum is NOT the Turbomole support. To get support for Turbomole please just send an email to turbomole (at) cosmologic (dot) de
This user forum was thought to be a platform where users can share their (Turbomole related) experiences and thoughts.
To answer your question anyway: This is due to the gridsize 'm3' in the $dft keyword section. What m3 does is to use a small grid for the DFT quadrature (i.e. the numerical integration of the density functional) during the SCF iterations. After convergence, ridft will switch to grid size 3 and do a single iteration to determine the final energy.
This is the default setting in Turbomole since it has been shown that the grid size does not have a large influence on the density but on the total energy only. So SCF converges to the same density with the small grid than it would for he larger grid. For structures and relative energies the final step for the total energy is sufficient (although you are of course right, if you look a the energies in the output it looks strange...).
For higher order properties or TDDFT it is recommended to use gridsize 4 - without an 'm' to be sure not to get too large errors from the quadrature. This is mentioned several times in the documentation and very shortly in the tutorial.
Regards,
Uwe
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Dear Uwe,
Thank you very much for your excellent help!
Best wishes,
Xichen