[CP2K:7212] Re: drastic change in pressure on changing smoothing
Matt W
MattWa... at gmail.com
Fri Dec 4 12:57:18 UTC 2015
Maybe someone else will chip in.
25 KPa is not a large pressure for a 64 mol box, I don't think.
Checking how it changes with cutoff would still look more convincing (and
check use finer grid is working correctly).
Matt
On Friday, December 4, 2015 at 12:48:41 PM UTC, Bernd Ensing wrote:
>
>
> Dear Matt,
>
> Thank you for your reply.
> We are comparing here two straightforward NVT runs (not NPT) of 64 water
> molecules in a box of 12.43 A. Without XC_SMOOTH_RHO, the average pressure
> is about zero Pa, instead with XC_SMOOTH_RHO the average pressure is
> about -25000 Pa.
> A third simulation using USE_FINER_GRID gives also about zero pressure
> (plus or minus a thousand).
>
> My guess is that there is a bug in the calculation of the XC part of the
> pressure tensor when using XC_SMOOTH_RHO. And it seems to me that it does
> not affect the forces in general, because dynamic properties such as the
> mean square displacement come out reasonable and only the pressure is
> dramatically affected.
>
> best wishes,
> Bernd
>
>
> On 4 Dec, 2015, at 13:01 , Matt W <Matt... at gmail.com <javascript:>>
> wrote:
>
> Hi,
>
> running NPT calculations are not straightforward. The stress tensor needs
> to be reasonably converged wrt the cutoff to get reliable results. The
> cutoff to converge the stress tensor might be much larger than for reliable
> forces.
>
> Matt
>
> On Thursday, December 3, 2015 at 5:00:18 PM UTC, Bernd Ensing wrote:
>>
>>
>> Dear cp2k developers,
>>
>> Is it known whether there is a bug in the calculation of the pressure
>> tensor when using XC_SMOOTH_RHO NN10?
>> Using this smoothing option results in very negative pressures for a
>> typical system containing 64 water molecules (see message below of Ambuj
>> Tiwari).
>> Does this strange behaviour also affect the forces on the atoms in
>> general?
>>
>> Many thanks in advance for your comments.
>> best wishes,
>>
>> Bernd Ensing
>>
>>
>>
>> Op woensdag 25 november 2015 13:49:36 UTC+1 schreef Ambuj Tiwari:
>>>
>>> Dear All,
>>> I am running a NVT MD simulation on bulkwater(64 water molecules) . The
>>> problem is related to pressure calculation.
>>> I was calculating the pressure for the system and found highly negative
>>> values(in order of -25000) and then I switched all the parameters one by
>>> one and eventually found out that on changing smoothing from XC_SMOOTH_RHO
>>> NN10 to USE_FINER_GRID it came down to less negative values(-5000). Is this
>>> some kind of bug in the program or more fundamental problem.
>>>
>>> I am attaching the input file and bottom of .ener .stress file here.
>>>
>>> Regards,
>>> Ambuj
>>>
>>>
>>> *'input file 1'*
>>>
>>> <https://en.wikipedia.org/wiki/Car%E2%80%93Parrinello_molecular_dynamics#cite_note-3>
>>> &XC
>>> &XC_FUNCTIONAL BLYP
>>> &END XC_FUNCTIONAL
>>> &VDW_POTENTIAL
>>> DISPERSION_FUNCTIONAL PAIR_POTENTIAL
>>> &PAIR_POTENTIAL
>>> TYPE DFTD3
>>> PARAMETER_FILE_NAME /home/ensing/BASIS_SET/dftd3.dat
>>> REFERENCE_FUNCTIONAL BLYP
>>> &END PAIR_POTENTIAL
>>> &END VDW_POTENTIAL
>>> &XC_GRID
>>>
>>> * XC_SMOOTH_RHO NN10 XC_DERIV SPLINE2_SMOOTH*
>>> &END XC_GRID
>>> &END XC
>>>
>>> *'input file 2'*
>>>
>>>
>>> &XC
>>> &XC_FUNCTIONAL BLYP
>>> &END XC_FUNCTIONAL
>>> &VDW_POTENTIAL
>>> DISPERSION_FUNCTIONAL PAIR_POTENTIAL
>>> &PAIR_POTENTIAL
>>> TYPE DFTD3
>>> PARAMETER_FILE_NAME /home/ensing/BASIS_SET/dftd3.dat
>>> REFERENCE_FUNCTIONAL BLYP
>>> &END PAIR_POTENTIAL
>>> &END VDW_POTENTIAL
>>> &XC_GRID
>>> * USE_FINER_GRID *
>>> &END XC_GRID
>>> &END XC
>>>
>>>
>>> *'*.ener 1'*
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> * 163298 81649.000000 0.295424393
>>> 325.610938118 -1101.039478079 -1100.781654417
>>> 22.112000000 163299 81649.500000 0.294462120
>>> 324.550339188 -1101.039370784 -1100.781669902
>>> 22.078000000 163300 81650.000000 0.294961268
>>> 325.100490947 -1101.040473093 -1100.781725319
>>> 25.159000000 163301 81650.500000 0.296162908
>>> 326.424914893 -1101.042161493 -1100.781750771
>>> 22.115700000 163302 81651.000000 0.298814382
>>> 329.347317264 -1101.044236790 -1100.781694623
>>> 22.139200000 163303 81651.500000 0.301128239
>>> 331.897603891 -1101.047561646 -1100.781602129
>>> 24.739700000 163304 81652.000000 0.307044448
>>> 338.418332848 -1101.053434140 -1100.781587012
>>> 24.682400000 163305 81652.500000 0.316425516
>>> 348.757961573 -1101.061982016 -1100.781699977
>>> 22.044200000 163306 81653.000000 0.327014965
>>> 360.429442967 -1101.071396202 -1100.781872287 22.101900000*
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> *'*.ener 2' 91 45.500000 0.316250053
>>> 348.564569099 -1102.663360533 -1102.332927916
>>> 65.288200000 92 46.000000 0.315037265
>>> 347.227857880 -1102.661696314 -1102.332913105
>>> 65.190400000 93 46.500000 0.314019534
>>> 346.106135819 -1102.660798344 -1102.332914267
>>> 65.276700000 94 47.000000 0.314010873
>>> 346.096588928 -1102.660760313 -1102.332937169
>>> 65.315200000 95 47.500000 0.315000947
>>> 347.187829574 -1102.661384548 -1102.332972600
>>> 65.163300000 96 48.000000 0.315886554
>>> 348.163928325 -1102.662099658 -1102.333054612
>>> 65.248800000 97 48.500000 0.315298803
>>> 347.516120600 -1102.661788013 -1102.333132240
>>> 65.120100000 98 49.000000 0.313543746
>>> 345.581730970 -1102.659461626 -1102.333136220
>>> 65.202000000 99 49.500000 0.309178417
>>> 340.770351269 -1102.655147713 -1102.333068024
>>> 63.328600000 100 50.000000 0.304077471
>>> 335.148189283 -1102.649908792 -1102.332978856
>>> 64.191200000
>>> '*.stress 1'*
>>> 163294 81647.000 -23587.6933211956 2342.2050511699
>>> -2620.1253216644 2342.2050511699 -23228.0050606190
>>> 3414.1775796133 -2620.1253216644 3414.1775796133 -20169.0313283565
>>> 163295 81647.500 -22389.3419955310 1849.7028598497
>>> -2508.5434330934 1849.7028598497 -24356.6599768539
>>> 2800.7048436858 -2508.5434330934 2800.7048436858 -22725.6161101663
>>> 163296 81648.000 -21214.9735696668 1148.0699336617
>>> -2218.3871712667 1148.0699336617 -25144.9624318558
>>> 1975.3590510643 -2218.3871712667 1975.3590510643 -24795.3384458679
>>> 163297 81648.500 -20309.0216433928 302.8654094409
>>> -1803.1704603762 302.8654094409 -25394.9473522949
>>> 996.8049404043 -1803.1704603762 996.8049404043 -26162.6367896449
>>> 163298 81649.000 -19855.8176878975 -598.7972734722
>>> -1300.5824885129 -598.7972734722 -24999.8852946563
>>> -79.5868061270 -1300.5824885129 -79.5868061270 -26686.2571452786
>>> 163299 81649.500 -19956.2226579495 -1461.2946422884
>>> -742.0897491587 -1461.2946422884 -24019.8747323228
>>> -1206.1348202948 -742.0897491587 -1206.1348202948 -26376.7375359960
>>> 163300 81650.000 -20534.1679738551 -2200.5578986806
>>> -164.8658164621 -2200.5578986806 -22584.1267162156
>>> -2322.5467222548 -164.8658164621 -2322.5467222548 -25268.9877352706
>>> 163301 81650.500 -21452.3785466678 -2746.9001879179
>>> 376.2080784084 -2746.9001879179 -20951.8376784856
>>> -3338.3737161118 376.2080784084 -3338.3737161118 -23492.0302819538
>>>
>>>
>>> *'*.stress 2'*
>>> 83 41.500 14620.6789775920 1631.8725215074
>>> 2233.0775150043 1631.8725215074 6922.5364171994
>>> 1568.9298877547 2233.0775150043 1568.9298877547 4863.0813795099
>>> 84 42.000 13465.9504463874 1646.6798565162
>>> 1742.3968878509 1646.6798565162 7528.7642280447
>>> 1356.1689695128 1742.3968878509 1356.1689695128 3678.0979512013
>>> 85 42.500 11929.6829243335 1557.1878823967
>>> 1189.8285351507 1557.1878823967 7536.6702267556
>>> 906.2538614813 1189.8285351507 906.2538614813 2706.1024195638
>>> 86 43.000 10242.7023865733 1377.0907756499
>>> 607.2431768383 1377.0907756499 6953.6306436901
>>> 280.8453243292 607.2431768383 280.8453243292 2111.5249630222
>>> 87 43.500 8704.9333307887 1111.3766575987
>>> 27.5775490784 1111.3766575987 5939.0119410377
>>> -388.5800033232 27.5775490784 -388.5800033232 2026.3208988151
>>> 88 44.000 7481.3245836153 770.0630298266
>>> -494.3356330308 770.0630298266 4626.9158749281
>>> -951.4354212867 -494.3356330308 -951.4354212867 2390.6634657579
>>> 89 44.500 6663.8847520724 360.1790480556
>>> -890.4213349779 360.1790480556 3225.2634082928
>>> -1279.9170414956 -890.4213349779 -1279.9170414956 3064.5349399335
>>> 90 45.000 6254.7640395386 -100.7086327357
>>> -1091.1835737339 -100.7086327357 1954.1849838233
>>> -1309.6032354774 -1091.1835737339 -1309.6032354774 3839.7803365830
>>> 91 45.500 6155.5011736691 -574.1695321638
>>> -1051.6467240489 -574.1695321638 957.4978282879
>>> -1053.9528084102 -1051.6467240489 -1053.9528084102 4443.4869908843
>>> 92 46.000 6285.5912946027 -1016.5428590808
>>> -783.4044479712 -1016.5428590808 376.4627244754
>>> -574.9649194818 -783.4044479712 -574.9649194818 4722.8910330993
>>> 93 46.500 6504.7623119346 -1380.8418795540
>>> -361.7805767782 -1380.8418795540 216.2588001339
>>> 37.9199806709 -361.7805767782 37.9199806709 4578.5854391507
>>> 94 47.000 6695.7329680208 -1630.3118660115
>>> 95.8727981760 -1630.3118660115 437.0880477724
>>> 702.9749077441 95.8727981760 702.9749077441 4059.5915440691
>>>
>>>
>>> Thanks in advance!
>>>
>>
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