Hi Sumit
Your CP2K calculation employs pseudopotentials (the O 1s electrons are not included) whereas your Gaussian calculation is most likely an all-electron calculation. Just check the electron count in the outputs. CP2K and Gaussian should list 8 and 10 electrons, respectively.
Matthias
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Hi Sumit
Add ‘PERIODIC none’ to the &CELL section and add the section
&POISSON
PERIODIC NONE
PSOLVER MT
&END POISSON
Moreover, drop the sections &INTERACTION_POTENTIAL and &VDW_POTENTIAL and set EPSFIT 1.0E-8 and EPS_DEFAULT 1.0E-12 in the &QS section.
That should result in an energy closer to the Gaussian.
HTH
Matthias
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Hi Sumit
That’s weird, because I get with my changes already a much lower energy
-76.4075988 Ha
and after including Jürg’s suggestions for the &XC section I get a total energy of
-76.4446450 Ha
Matthias
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Hi
Use the &XC section as suggested by Jürg:
#These are the coefficients used for B3LYP using VWN3, this is the default Gaussian definition, but not recommended
&XC
&XC_FUNCTIONAL
&LYP
SCALE_C 0.81
&END
&BECKE88
SCALE_X 0.72
&END
&VWN
FUNCTIONAL_TYPE VWN3
SCALE_C 0.19
&END
&XALPHA
SCALE_X 0.08
&END
&END XC_FUNCTIONAL
&HF
&SCREENING
EPS_SCHWARZ 1.0E-12
&END
&MEMORY
MAX_MEMORY 100
&END
FRACTION 0.20
&END
&END XC
Use VWN3 instead of VWN5 and define the HF fraction of 0.2.
Matthias
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Hi Sumit
Molecules and clusters in gas phase are usually treated as isolated systems without PBC independent of their size. To that end, you have to choose a sufficiently large simulation cell using “PERIODIC none” (add at least 8 A to the diameter of the molecule/cluster in each Cartesian direction). EPS_DEFAULT 1.0E-12 is a reasonable choice for most cases. The density cut-off depends on the employed (pseudo)potentials. The electron count printed at the end of the SCF run is a good indicator, if you need to further decrease EPS_DEFAULT or increase the cut-off. No &MOTION but a &VIBRATIONAL_ANALYSIS section is needed for RUN_TYPE VIBRATIONAL_ANALYSIS.
Have a look at the tutorials or search this forum for further information.
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Hi Sumit
Then there is still something wrong with your input. I get for an isolated water molecule with B3LYP (Gaussian setup) and aug-cc-pVDZ basis set: r(OH) = 0.965 A, a(HOH) = 104.75°, Energy = -76.444645 a.u.
.
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Try to decrease the four convergence threshold values in the &MOTION section by at least an order of magnitude.
Matthias
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H2o-dimer(cp2k) |
H2O-dimer(gaussian) |
Energy = -152.89098920 |
Energy = -152.8967947 |
Frequencies |
Frequencies |
-44 |
128 |
15 |
156 |
95 |
157 |
98 |
184 |
136 |
360 |
224 |
634 |
1619 |
1617 |
1622 |
1637 |
3787 |
3672 |
3792 |
3789 |
3898 |
3874 |
3900 |
3895 |
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