events:2018_summer_school:converging_cutoff
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| exercises:2018_uol_school:converging_cutoff [2018/05/31 10:06] – [Analysis] mwatkins | events:2018_summer_school:converging_cutoff [2020/08/21 10:15] (current) – external edit 127.0.0.1 | ||
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| This exercise is similar to the previous one, but uses a setup and system more typical of CP2K usage. We will use a system of 32 H< | This exercise is similar to the previous one, but uses a setup and system more typical of CP2K usage. We will use a system of 32 H< | ||
| - | < | + | < |
| &GLOBAL | &GLOBAL | ||
| PRINT_LEVEL MEDIUM | PRINT_LEVEL MEDIUM | ||
| Line 91: | Line 91: | ||
| Compared to the Si example, this is a larger system, we are using the OT optimizer in a good setup for a small to medium insulating system: | Compared to the Si example, this is a larger system, we are using the OT optimizer in a good setup for a small to medium insulating system: | ||
| - | < | + | < |
| &SCF | &SCF | ||
| SCF_GUESS RESTART | SCF_GUESS RESTART | ||
| Line 109: | Line 109: | ||
| and we are also saving the forces on the atoms | and we are also saving the forces on the atoms | ||
| - | < | + | < |
| &FORCES | &FORCES | ||
| Line 177: | Line 177: | ||
| </ | </ | ||
| - | That there is a Gaussian with an exponent of 10.4 Bohr< | + | That there is a Gaussian with an exponent of 10.4 Bohr< |
| + | |||
| + | < | ||
| + | Si DZVP-MOLOPT-GTH DZVP-MOLOPT-GTH-q4 | ||
| + | 1 | ||
| + | 2 0 2 6 2 2 1 | ||
| + | 2.693604434572 | ||
| + | 1.359613855428 -0.283798205000 | ||
| + | 0.513245176029 -0.228939692700 -0.276015880000 | ||
| + | 0.326563011394 | ||
| + | 0.139986977410 | ||
| + | 0.068212286977 | ||
| + | </ | ||
| + | |||
| + | we see that the largest exponent is only 2.7 Bohr< | ||
| + | |||
| + | < | ||
| + | If you like, have a look at the BASIS_MOLOPT file (in the data directory, or online [[https:// | ||
| + | </ | ||
| + | |||
| + | The convergence is largely dominated by the calculation of the gradient terms in a GGA functional (compare a simulation with LDA to the PBE used here). The evaluation of these terms on the grids are demanding, and very dependent on the functional. | ||
| + | |||
| + | < | ||
| + | &XC | ||
| + | & | ||
| + | &END XC_FUNCTIONAL | ||
| + | & | ||
| + | ! defaults | ||
| + | XC_SMOOTH_RHO NONE | ||
| + | XC_DERIV PW | ||
| + | &END XC_GRID | ||
| + | &END XC | ||
| + | </ | ||
| + | |||
| + | For BLYP functional some smoothing needs to be applied. The smoothing may also converge forces more rapidly than the default settings, but at the expense of modifying the functional slightly. | ||
| + | |||
| + | < | ||
| + | |||
| + | compare to the previous calculation, | ||
| + | |||
| + | < | ||
| + | &XC | ||
| + | & | ||
| + | &END XC_FUNCTIONAL | ||
| + | & | ||
| + | XC_SMOOTH_RHO NN50 | ||
| + | XC_DERIV NN50_SMOOTH | ||
| + | &END | ||
| + | &END XC | ||
| + | </ | ||
| + | |||
| + | compare the convergence of LDA and BLYP to PBE. | ||
| + | |||
| + | < | ||
| + | & | ||
| + | &END XC_FUNCTIONAL | ||
| + | </ | ||
| + | </ | ||
| + | |||
| + | <note tip> | ||
| + | Also change the psuedo potential to the appropriate functional. | ||
| + | < | ||
| + | &KIND O | ||
| + | BASIS_SET DZVP-MOLOPT-SR-GTH-q6 | ||
| + | POTENTIAL GTH-PADE-q6 | ||
| + | &END KIND | ||
| + | </ | ||
| + | PADE is a synonym for LDA. | ||
| + | </ | ||
events/2018_summer_school/converging_cutoff.1527761166.txt.gz · Last modified: 2020/08/21 10:14 (external edit)