--- Tinker-HP : detected abnormal fluctuation on energy

[Cynthia-0807]

When I run NPT ensemble in tinker-hp, it reported this error:

     54420  -227953.3527  -336988.1341   109034.7814     300.16
     54430  -228057.0155  -336766.7087   108709.6931     299.26
     54440  -228061.4643  -336653.3258   108591.8615     298.94
     54450  -227890.9089  -337053.8231   109162.9142     300.51
     54460  -227917.9314  -336851.2429   108933.3115     299.88
     54470  -227728.4285  -336728.5535   109000.1250     300.06

  --- Tinker-HP :  detected abnormal fluctuation on energy
 epot/ average/ 10*std   -298019.8815204528        -336551.3226793714
    2569.754883292985
 ealt   =     96455.54382721892
 ev/ec  =     162718.2200822882         0.000000000000000
 em+ep  =    -557193.6454299600

This is my input file:

parameters  amoebabio18_add.prm
integrator respa
neighbor-list
verbose
x-axis                       117
y-axis                       115
z-axis                       107
polar-eps                      0.00001
vdw-cutoff                     12.0
vdw-correction
ewald
ewald-cutoff                    7.0
pme-grid   118 116 108  #slightly bigger than box size,must be even with factors of only 2,3 and 5
#restrain-position   -1 11984 25 0
randomseed 12345
thermostat    bussi
barostat                        montecarlo
tau-pressure                    1.0
printout                       1000
dcdio

the command:

mpirun -np 1 dynamic.mixed m1_npt.xyz -k npt.key 1000000 2.0 10.0 4 300.0 1.0> npt.log

Because my system includes two organic molecules, I add some new parameters generated by poltype2. Maybe error parameters?

[louislagardere]

Hi,
Your keyfile looks fine as well as your command, it could be an issue with the parameters indeed, or something that went wrong during equilibration. A suggestion is to try the Berendsen barostat ("barostat berendsen") that works fine during this phase.

Louis

[Cynthia-0807]

Hi, Your keyfile looks fine as well as your command, it could be an issue with the parameters indeed, or something that went wrong during equilibration. A suggestion is to try the Berendsen barostat ("barostat berendsen") that works fine during this phase.

Louis

Thanks for your suggestion.However, it reported different error after I changed the barostat:

 tro prmem_int_req   2124532800            0

This means a lack of memory?

[louislagardere]

It is most probably just an indirect consequence of an "MD explosion" that may be due to an issue with the parameters.

[Cynthia-0807]

It is most probably just an indirect consequence of an "MD explosion" that may be due to an issue with the parameters.

Thanks for your reply, I check the parameters.

[Cynthia-0807]

It is most probably just an indirect consequence of an "MD explosion" that may be due to an issue with the parameters.

Besides, When I use montecarlo barostat, the box become longer and narrower. Is there any keyword to adjust the isotropy of pressure?