Hi, I dont know if I should post my query in this but since this is related to pressure in my NPT simulation, I would think it is fine.

I am trying to run simulation using SSBP (Spherical Solvent Boundary Potential) and using HOOVER thermostat to maintain my temperature.
When I try to use PCONS command, it says pcons can be used only for CRYSTAL facility.
Since I am not using PBC, and SSBP by itself says that it is a constant temperature and pressure system, could you suggest how to define NPT for my system?

Currently my input file is like this.

!Defining spherical solvent boundary potential
MMFP
SSBP SELE TYPE OH2 END
GEO sphere RCM -
xref 0.0 yref 0.0 zref 0.0 -
force 10.0 droff 0.0 -
select segid PI .or. segid NI end
END

!Defining non-bonded interactions
NBONDS GROUP SWITCH CDIE VDW VSWI EXTEND GRAD QUAD -
CUTNB 22.0 CTOFNB 20.0 CTONNB 18.0 WMIN 1.5 EPS 1.0

!Calculating piston mass statistics
SCALar MASS STAT
CALCulate pmass = int (?STOT / 50.0)
CALCulate tmass = @pmass * 10

!Adaptive umbrella sampling for distance
rxncor: define set1 point sele atom PI 1 SOD end
rxncor: define set2 point sele atom NI 1 CLA end
rxncor: define rc distance set1 set2
rxncor: set rc
rxncor: trace rc unit 31
rxncor: UMBRella name rc KUMB @kumb DEL0 @del0 FORM 1
calc lowdel = @del0 - 1.5
calc hidel = @del0 + 1.5
rxncor: statistics name rc lowdelta @lowdel hidelta @hidel deldel 0.05 start 500

!Heating the system using thermostat
OPEN READ FORMatted UNIT 21 NAME @equ.res
OPEN WRITe FORMatted UNIT 20 NAME @umb.res
OPEN WRITe UNFOrmatted UNIT 22 NAME @umb.dcd

DYNA LEAP STARt -
NSTEP 150000 TIMESTep 0.002 NPRINT 1000 -
HOOVER REFT 300.0 TMASS @tmass
! PConst pmass 400.0 pgamma 20.0 tbath 300.0 PREFerence 1.0
IUNREAd -1 IUNWRIte 20 IUNCRD 22 NSAVC 50 -
IEQFRQ 0 IPRFRQ 1000 NTRFRQ 1000 INBFRQ -1 IMGFRQ -1 -
IASORS 0 IASVEL 1 ISCVEL 0 ICHECW 1 ECHECK 2000

When I run using the above given input file, my output prints the following.

AVER DYN: Step Time TOTEner TOTKe ENERgy TEMPerature
AVER PROP: GRMS HFCTote HFCKe EHFCor VIRKe
AVER INTERN: BONDs ANGLes UREY-b DIHEdrals IMPRopers
AVER EXTERN: VDWaals ELEC HBONds ASP USER
AVER IMAGES: IMNBvdw IMELec IMHBnd RXNField EXTElec
AVER MMFP: GEO MDIP SSBP SHEL DROFfa
AVER PRESS: VIRE VIRI PRESSE PRESSI VOLUme
AVER UMBR: ADUMB RXNCor
---------- --------- --------- --------- --------- ---------
AVER> 1000 410.00000 -1728.20443 761.54885 -2489.75329 290.65515
AVER PROP> 19.18438 -1693.69510 865.06832 34.50934 870.21533
AVER INTERN> 322.74996 168.45926 0.00000 0.00000 0.00000
AVER EXTERN> 429.86435 -3599.40787 0.00000 0.00000 0.00000
AVER IMAGES> 0.00000 0.00000 0.00000 0.00000 -0.30749
AVER MMFP> 1.04264 0.00000 187.66405 0.00000 0.00000
AVER PRESS> -21.01478 -559.12877 0.00000 0.00000 0.00000
AVER UMBR> 0.00000 0.18182


How can the pressure be maintained at 0 atm?
There is something seriously wrong with my system and I need help to set up constant pressure and temperature for my system properly.


Last edited by vidhya; 09/07/18 10:24 AM.