[CP2K:3890] Re: high binding energy
Sandeep Kumar Reddy
kuma... at gmail.com
Wed Jul 4 06:50:02 UTC 2012
Dear Matt,
For Br, DZVP is the large basis set available in cp2k.
>From last two days, i am continuously running tests on different ion pairs.
All calculations show considerable difference compared to MP2 results.
I will repeat the calculations with extra diffuse functions wherever
possible.
(when i did the calculations on different ion-pairs, i got huge differences
in some cases also ( -40 kcal/mol difference)
Regards,
Sandeep
On Wed, Jul 4, 2012 at 12:06 PM, Matt W <MattWa... at gmail.com> wrote:
> Hi Sandeep,
>
> there is nothing very obviously wrong with your input.
>
> Maybe the basis set is not good enough for the anion? You could see
> whether extra diffuse functions make a big difference...
>
> Matt
>
> On Tuesday, July 3, 2012 11:13:18 AM UTC+1, sandeep wrote:
>>
>> Hi,
>> Towards solving this, I have done binding energy calculations for
>> molecular systems (where they interact through hydrogen bonds) and this
>> value matches with MP2 results.
>>
>> It looks like the problem comes in for ionic systems. Did i missed any
>> keyword in my input file ?
>>
>> Hope this helps somebody to comment on my input file ...
>>
>> Thanks & Regards,
>> Sandeep
>>
>>
>>
>> On Mon, Jul 2, 2012 at 6:31 PM, Sandeep Kumar Reddy <kuma... at gmail.com>wrote:
>>
>>> Dear all,
>>> I want to calculate binding energy and compare with
>>> Gaussian's result and then i would like to proceed to bulk simulations.
>>>
>>> My system one ion pair (it's an ionic liquid). I did geometry
>>> optimizations of cation, anion and ion-pair and calculated the binding
>>> energy. This value is equal to *-119* *kcal/mol*. After adding BSSE
>>> corrections, it is reduced to *-116* kcal/mol. For comparison, i
>>> carried out same calculations at MP2/aug-cc-pVDZ level using Gaussian
>>> package and this value is equal to -104 kcal/mol (BSSE corrected). A
>>> difference of 10 kcal/mol of such calculation is discouraging.
>>>
>>> (I have used same functional, cell parameters, cutoff, potentials for
>>> all three calculations)
>>>
>>>
>>> I repeated the calculations by changing cutoff (to 480 Ry) and
>>> increasing box length (20 \AA). But it gives me same binding energy.
>>> Additionally, i have done same calculations in plane wave basis set using
>>> CPMD code. It gives 105 kcal/mol, very close to MP2 result.
>>>
>>> I am not able to figure out why it happens. Could anybody comment on my
>>> input files ?
>>>
>>>
>>> *Ion-pair :*
>>>
>>> &GLOBAL
>>> PROJECT dimethyl_ammonium_bromide
>>> RUN_TYPE GEO_OPT
>>> PRINT_LEVEL MEDIUM
>>> &END GLOBAL
>>>
>>> &FORCE_EVAL
>>> METHOD Quickstep
>>> &DFT
>>> BASIS_SET_FILE_NAME /panfs/home/Xsreddy/cp2k/tests/QS/BASIS_MOLOPT
>>> POTENTIAL_FILE_NAME /panfs/home/Xsreddy/cp2k/tests/QS/POTENTIAL
>>> &MGRID
>>> CUTOFF 280
>>> NGRIDS 5
>>> &END MGRID
>>> &QS
>>> METHOD GPW
>>> EPS_DEFAULT 1.0E-10
>>> &END QS
>>> &SCF
>>> MAX_SCF 50
>>> EPS_SCF 1.0E-6
>>> SCF_GUESS ATOMIC
>>> &OT ON
>>> MINIMIZER CG
>>> PRECONDITIONER FULL_ALL
>>> ENERGY_GAP 0.001
>>> &END OT
>>> &OUTER_SCF
>>> MAX_SCF 100
>>> EPS_SCF 1.0E-6
>>> &END OUTER_SCF
>>> &END SCF
>>> &XC
>>> &XC_FUNCTIONAL BLYP
>>> &END XC_FUNCTIONAL
>>> &vdW_POTENTIAL
>>> DISPERSION_FUNCTIONAL PAIR_POTENTIAL
>>> &PAIR_POTENTIAL
>>> TYPE DFTD2
>>> REFERENCE_FUNCTIONAL BLYP
>>> &END PAIR_POTENTIAL
>>> &END vdW_POTENTIAL
>>> &END XC
>>> &POISSON
>>> POISSON_SOLVER WAVELET
>>> PERIODIC NONE
>>> &END POISSON
>>> &END DFT
>>> &SUBSYS
>>> &CELL
>>> ABC 20.0 20.0 20.0
>>> PERIODIC NONE
>>> &END CELL
>>> &COORD
>>> H 1.82622900 0.00011700 1.45609900
>>> H 0.41368700 -0.00011700 0.43855600
>>> N 1.53927100 0.00002300 0.47861600
>>> C 1.97625500 -1.24136700 -0.20041700
>>> H 3.06445100 -1.28419200 -0.25417500
>>> H 1.58040100 -2.09266400 0.34985900
>>> H 1.53907000 -1.23367800 -1.19754500
>>> C 1.97589400 1.24149000 -0.20039300
>>> H 1.54099200 1.23242900 -1.19850300
>>> H 1.57755100 2.09264100 0.34831700
>>> H 3.06414500 1.28582600 -0.25177600
>>> Br -1.40269500 -0.00003600 -0.01818000
>>> &END COORD
>>> &TOPOLOGY
>>> &CENTER_COORDINATES
>>> &END
>>> &END
>>> &KIND H
>>> BASIS_SET DZVP-MOLOPT-GTH
>>> POTENTIAL GTH-BLYP-q1
>>> &END KIND
>>> &KIND C
>>> BASIS_SET DZVP-MOLOPT-GTH
>>> POTENTIAL GTH-BLYP-q4
>>> &END KIND
>>> &KIND N
>>> BASIS_SET DZVP-MOLOPT-GTH
>>> POTENTIAL GTH-BLYP-q5
>>> &END KIND
>>> &KIND Br
>>> BASIS_SET DZVP-MOLOPT-SR-GTH
>>> POTENTIAL GTH-BLYP-q7
>>> &END KIND
>>> &END SUBSYS
>>> &END FORCE_EVAL
>>> &MOTION
>>> &GEO_OPT
>>> MAX_FORCE 0.0001
>>> MAX_ITER 500
>>> OPTIMIZER BFGS
>>> &END GEO_OPT
>>> &END MOTION
>>>
>>>
>>> Other input files are enclosed.
>>>
>>> Thanks.
>>>
>>> Regards,
>>> Sandeep
>>>
>>>
>>> *
>>> *
>>>
>>>
>>>
>>>
>>>
>>>
>> --
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