[CP2K:7213] Re: drastic change in pressure on changing smoothing

hut... at chem.uzh.ch hut... at chem.uzh.ch
Mon Dec 7 08:05:08 UTC 2015


Hi Bernd

yes, this must be a bug in the code. All smoothing operations
on the density or the gradient of the density depend on the 
grid. That means that there is an additional term in the 
stress tensor from this. It seems that this case has been 
forgotten when the stress tensor was implemented.
Unfortunately, I cannot promise that this will be implemented
soon.

Juerg
--------------------------------------------------------------
Juerg Hutter                         Phone : ++41 44 635 4491
Institut für Chemie C                FAX   : ++41 44 635 6838
Universität Zürich                   E-mail: hut... at chem.uzh.ch
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------

-----cp... at googlegroups.com wrote: -----To: cp... at googlegroups.com
From: Bernd Ensing 
Sent by: cp... at googlegroups.com
Date: 12/04/2015 01:48PM
Subject: Re: [CP2K:7213] Re: drastic change in pressure on changing smoothing


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 <MattWa... at gmail.com> 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'
 
    &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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