Is it normal to see positive value of VDW energy in traj? - 09/28/19 02:55 AM

Hi,

Is it normal to see positive value of VDW energy in traj?

My MD traj result seems OK, and total energy fluctuates around a constant value, but the VDW energy always be a positive number, while the ELEC energy is a much bigger minus number, so the total energy is still minus.

I set up my MD NVT running with:

nbond inbfrq -1 imgfrq -1 atom vatom cdie eps 1.0 -

elec ewald pmew fftx 48 ffty 48 fftz 48 kappa .34 spline order 6 -

vdw vswitch cutnb 14.0 cutim 14.0 ctofnb 12. ctonnb 10. wmin 1.0

scalar mass stat

set pmass 0

calc tmass = int( ?stot / 50.0 ) * 5

dyna leap cpt restart - !

timestep 0.001 nstep 20000 nprint 10000 iprfq 2000 - !

iunrea 51 iunwri 41 iuncrd 31 nsavcc 1 - !

hoover reft @tk tmass @tmass tbat @tk firs @tk tstr @tk - !

pcons pmzz @pmass pmxx 0.0 pmyy 0.0 pref 1.0 - !

pint pref 1.0 pgamma 0.0 - !

ihtfrq 0 ieqfrq 0 ntrfrq 50 - !

iasors 1 iasvel 1 iscvel 0 ichecw 0 - !

ixtf 1000 echeck 100. !

Is that make sense or I set something wrong?

Also, I pick some clusters out and calculate energy of them, without PME set, the VDW energy shows a great number about xx+E066, and ELEC energy seems OK but can no longer balance the total energy to a reasonable value, why?

Thanks for any kindly help

Is it normal to see positive value of VDW energy in traj?

My MD traj result seems OK, and total energy fluctuates around a constant value, but the VDW energy always be a positive number, while the ELEC energy is a much bigger minus number, so the total energy is still minus.

I set up my MD NVT running with:

nbond inbfrq -1 imgfrq -1 atom vatom cdie eps 1.0 -

elec ewald pmew fftx 48 ffty 48 fftz 48 kappa .34 spline order 6 -

vdw vswitch cutnb 14.0 cutim 14.0 ctofnb 12. ctonnb 10. wmin 1.0

scalar mass stat

set pmass 0

calc tmass = int( ?stot / 50.0 ) * 5

dyna leap cpt restart - !

timestep 0.001 nstep 20000 nprint 10000 iprfq 2000 - !

iunrea 51 iunwri 41 iuncrd 31 nsavcc 1 - !

hoover reft @tk tmass @tmass tbat @tk firs @tk tstr @tk - !

pcons pmzz @pmass pmxx 0.0 pmyy 0.0 pref 1.0 - !

pint pref 1.0 pgamma 0.0 - !

ihtfrq 0 ieqfrq 0 ntrfrq 50 - !

iasors 1 iasvel 1 iscvel 0 ichecw 0 - !

ixtf 1000 echeck 100. !

Is that make sense or I set something wrong?

Also, I pick some clusters out and calculate energy of them, without PME set, the VDW energy shows a great number about xx+E066, and ELEC energy seems OK but can no longer balance the total energy to a reasonable value, why?

Thanks for any kindly help