[CP2K-user] [CP2K:11135] Re: Reproducing Born-Haber cycle energies for teaching purposes

[Henrique C. S. Junior]

 Dear Matt,
Thank you for your kind and insightful reply, it really helped a lot.

On Tue, Jan 8, 2019 at 7:41 AM Matt W <mattwa... at gmail.com> wrote:

> Hi Henrique,
>
> there are several issues with your calculation. I'll try and put up a full
> how-to on this as it addresses several useful points:
>
> (i) calculating Na+ accurately requires using non-periodic boundary
> conditions. Set periodic none in &CELL and &POISSON section, along with
> PSOLVER wavelet
> (ii) you need a larger unit cell to accurately represent NaCl using gamma
> point only - I used MULTIPLE_UNIT_CELL 4 4 4 (you could use k-points
> instead)
> (iii) you need a _much_ larger cutoff for Na - 1500 Ry is still not
> adequate for fully converged stress tensor(!)
>
> To avoid the non cubic optimization you saw, you need to explicitly set
> SYMMETRY CUBIC in the &CELL section. CP2K doesn't find the symmetry by
> itself so doesn't keep it.
>
> With these changes I got an enthalpy of ~-990 kJ/mol which is within ~12%
> of the value you quote with a difference of only ~10 kJ/mol between DZVP
> and TZV2P basis, so I guess this is likely close to the PBE value. This is
> a zero K value, not sure about the experimental data.
>
> HTH,
>
> Matt
>
> On Sunday, January 6, 2019 at 4:22:52 PM UTC, Henrique Junior wrote:
>>
>> Dear colleagues,
>>
>> For teaching purposes I’m trying to reproduce Born-Haber Cycle energies
>> using CP2K (6.1). Since this is just for didactic purposes, the simplest
>> cases, like NaCl, KBr etc are more than enough, but here is what I’ve got
>> so far:
>>
>>
>> * Starting from .cif files for the solid parts (available online) I have
>> user GEO and CELL Opt to get an optimized energy:
>>
>> &GLOBAL
>>
>> PROJECT NaCl
>>
>> RUN_TYPE CELL_OPT
>>
>> PRINT_LEVEL LOW
>>
>> &END GLOBAL
>>
>>
>> &MOTION
>>
>> &CELL_OPT
>>
>> KEEP_ANGLES true
>>
>> KEEP_SYMMETRY true
>>
>> MAX_ITER 2000
>>
>> OPTIMIZER BFGS
>>
>> TYPE DIRECT_CELL_OPT
>>
>> EXTERNAL_PRESSURE 10000.0 0.0 0.0 0.0 10000.0 0.0 0.0 0.0 10000.0
>>
>> PRESSURE_TOLERANCE 10000
>>
>> &END CELL_OPT
>>
>> &GEO_OPT
>>
>> OPTIMIZER BFGS
>>
>> &END GEO_OPT
>>
>> &END MOTION
>>
>>
>> * For the gaseous parts I have performed only GEO_OPT in a large (fixed)
>> unitary cell.
>>
>>
>> *It is interesting to note that despite using KEEP_ANGLES true and
>> KEEP_SYMMETRY true the final cell is not perfectly cubic (why?).*
>>
>>
>> Testing for the energy of part of the cycle (NaCl energy is divided by 4,
>> and Cl2 is divided by 2):
>>
>>
>> Na+(g) + ½ Cl2(g) → NaCl(s)
>>
>> (-47.3764756753857 + -14.9639608215114) → -62.3002586417268
>>
>> Results in -0.04017785517032 Eh or -105.48693988 KJ/mol
>>
>>
>> An energy that is not even close to what is expected (The entire
>> born-haber cycle is attached).
>>
>>
>> So, here is the question: What am I doing wrong? Can the Born-haber cycle
>> energies be obtained using CP2k (maybe with a different approach?)?
>>
>> Thanks in advance for any help
>>
>>
>>
>>
>> Here is the complete input:
>>
>> &GLOBAL
>>
>> PROJECT NaCl
>>
>> RUN_TYPE CELL_OPT
>>
>> PRINT_LEVEL LOW
>>
>> &END GLOBAL
>>
>>
>> &MOTION
>>
>> &CELL_OPT
>>
>> KEEP_ANGLES true
>>
>> KEEP_SYMMETRY true
>>
>> MAX_ITER 20000
>>
>> OPTIMIZER BFGS
>>
>> TYPE DIRECT_CELL_OPT
>>
>> EXTERNAL_PRESSURE 10000.0 0.0 0.0 0.0 10000.0 0.0 0.0 0.0 10000.0
>>
>> PRESSURE_TOLERANCE 10000
>>
>> &END CELL_OPT
>>
>> &GEO_OPT
>>
>> OPTIMIZER BFGS
>>
>> &END GEO_OPT
>>
>> &END MOTION
>>
>>
>> &FORCE_EVAL
>>
>> STRESS_TENSOR DIAGONAL_ANALYTICAL
>>
>> METHOD QS
>>
>>
>> &DFT
>>
>>
>> &QS
>>
>> EPS_DEFAULT 1.0E-12
>>
>> EXTRAPOLATION ASPC
>>
>> EXTRAPOLATION_ORDER 3
>>
>> METHOD GPW
>>
>> PW_GRID NS-FULLSPACE
>>
>> MAP_CONSISTENT
>>
>> &END QS
>>
>>
>> CHARGE 0
>>
>> MULTIPLICITY 1
>>
>> BASIS_SET_FILE_NAME BASIS
>>
>> POTENTIAL_FILE_NAME POTENTIAL
>>
>>
>> &MGRID
>>
>> COMMENSURATE
>>
>> CUTOFF 600
>>
>> NGRIDS 5
>>
>> REALSPACE
>>
>> RELATIVE_CUTOFF 80
>>
>> &RS_GRID
>>
>> DISTRIBUTION_TYPE AUTOMATIC
>>
>> &END RS_GRID
>>
>> &END MGRID
>>
>>
>> &XC
>>
>> &XC_FUNCTIONAL PBE
>>
>> &END XC_FUNCTIONAL
>>
>> &END XC
>>
>> &SCF
>>
>> EPS_SCF 1.0E-7
>>
>> MAX_DIIS 4
>>
>> MAX_SCF 50000
>>
>> SCF_GUESS RESTART
>>
>> &OT
>>
>> ALGORITHM IRAC
>>
>> ORTHO_IRAC POLY
>>
>> ENERGY_GAP 0.001
>>
>> LINESEARCH 2PNT
>>
>> MINIMIZER CG
>>
>> PRECONDITIONER FULL_ALL
>>
>> &END OT
>>
>> &OUTER_SCF T
>>
>> EPS_SCF 1.0000000000000000E-07
>>
>> MAX_SCF 50000
>>
>> OPTIMIZER DIIS
>>
>> &END OUTER_SCF
>>
>> &END SCF
>>
>> &END DFT
>>
>>
>> &SUBSYS
>>
>> &COORD
>>
>> Na 0.00000000 0.00000000 0.00000000
>>
>> Na 0.00000000 2.81000000 2.81000000
>>
>> Na 2.81000000 0.00000000 2.81000000
>>
>> Na 2.81000000 2.81000000 0.00000000
>>
>> Cl 2.81000000 2.81000000 2.81000000
>>
>> Cl 2.81000000 0.00000000 0.00000000
>>
>> Cl 0.00000000 2.81000000 0.00000000
>>
>> Cl 0.00000000 0.00000000 2.81000000
>>
>> &END COORD
>>
>>
>> &KIND Na
>>
>> BASIS_SET DZVP-MOLOPT-SR-GTH-q9
>>
>> POTENTIAL GTH-PBE-q9
>>
>> &END KIND
>>
>> &KIND Cl
>>
>> BASIS_SET DZVP-MOLOPT-SR-GTH-q7
>>
>> POTENTIAL GTH-PBE-q7
>>
>> &END KIND
>>
>>
>> &CELL
>>
>> ABC 5.62 5.62 5.62
>>
>> ALPHA_BETA_GAMMA 90.00000 90.00000 90.00000
>>
>> &END CELL
>>
>> &END SUBSYS
>>
>>
>> &END FORCE_EVAL
>>
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-- 
*Henrique C. S. Junior*
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