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runbody1, nbody1 - (frontend to) Aarseth N-body code
runbody1 [parameter=value]
nbody1 < nbody1.in
runbody1 is a frontend to the NBODY1 fortran program.
Output
snapshots are by default not created, and must be turned on with a options
flag (see kz= below). All of the input parameter names are the same as their
counterpart in the NBODY1 program.
The following parameters are
recognized in any order if the keyword is also given:
- in=
- input file (optional,
see nbody= to generate your own input data on the fly). If input data are
given, you must also set KZ(4)
=2 (see below). Default: not used.
- outdir=
- Output run directory. This directory should not exist, although can be overriden
with NEMO’s standard error= system keyword. No default.
- nbody=
- ** Total particle
number. The maximum value (NMAX) is compiled into the NBODY1 program. Note
that even if input files are supplied, this parameter is needed. No default.
- nfix=
- Output frequency of data save (KZ(3)
) or binaries (KZ(6)
). [Default:
1]
- nrand=
- Random number sequence skip. [Default: 0]
- nrun=
- Run identification
index. Not really used for anything, just a relic from nameless Aarseth-type
files. The outdir now has this function. [Default: 1]
- eta=
- ** Time-step parameter
for force polynomial. [Default: 0.02]
- deltat=
- Output time interval in units
of the crossing time (M**2.5/(2E)**1.5). [Default: 0.25]
- tcrit=
- Termination
time in units of the crossing time. [Default: 5]
- qe=
- Energy tolerance (restart
if DE/E > 5*QE & KZ(2)
> 1) [Default: 2e-5]
- eps=
- Potential softening parameter
[Default: 0.01]
- kz=
- ** Non-zero options for alternative paths (see below)
[Default: 1,0,0,0,1,1,0,0,0,0,0,0,0,0,0]
1 COMMON save on unit 1 if TCOMP > CPU or if TIME > TCRIT. [1]
2 COMMON save on unit 2 at output (=1); restart if DE/E > 5*QE (=2).
[0]
3 Basic data written to unit 3 at output time (frequency NFIX). [0]
4 Initial conditions on unit 4 (=1: output; =2: input). [0]
5 Initial conditions (=0: uniform & isotropic; =1: Plummer). [1]
6 Output of significant binaries. [1]
7 Output of movie frames on unit 7. [0]
8 Generation of two subsystems (merger experiment). [0]
9 Individual bodies printed at output time (MIN(5**KZ9,N)). [0]
10 No scaling of initial conditions. [0]
11 Modification of ETA by tolerance QE. [0]
12 Initial parameters for binary orbit. [0]
13 Escaper removal (R > 2*RTIDE; RTIDE = 10*RSCALE). [0]
14 Adjustment of coordinates & velocities to c.m. condition. [0]
15 Not used at present [0]
- alphas=
- ** Power-law index for initial mass function (routine DATA) [Default:
2.3]
- body1=
- Maximum particle mass before scaling [Default: 5.0]
- bodyn=
- Minimum particle mass before scaling [Default: 1.0]
- q=
- ** Virial ratio
(q=0.5 for virial equilibrium) [Default: 0]
- vxrot=
- XY-velocity scaling
factor (> 0 for solid-body rotation) [Default: 0]
- vzrot=
- Z-velocity scaling
factor (not used if VXROT = [Default: 0]
- rbar=
- Virial radius in pc (for
scaling to physical [Default: 1]
- zmbar=
- Mean mass in solar units [Default:
1]
- xcm=
- ** Displacement for subsystem (routine SCALE; KZ(8)
)
- ecc=
- Eccentricity
of relative motion for subsystem (ECC =< 1)
- kstart=
- ** Run mode: 1=new >1
restart, with increasing options of resetting variables. Only new runs
are currently supported.
- tcomp=
- not supposed to be used, but counts max
computing time alotted.
Scaling can cause output to become out of bounds.
Coding the the input-order logic in the frontend program can be hazardous
to your health. It will depend on how the nbody1 main program is structured.
Order of input lines in "nbody1.in" for a new run (KSTART=1)
variables condition where
---------------------------- ------------------- ---------
KSTART TCOMP MAIN
Nbody NFIX NRAND NRUN INPUT
ETA DELTAT TCRIT QE EPS INPUT
KZ(1..15) INPUT
ALPHAS BODY1 BODYN KZ(4).NE.2 DATA
SEMI ECC KZ(12).NE.0 DATA
Q VXROT VZROT RBAR ZMBAR SCALE
NFRAME DELTAF KZ(7).GT.0 SCALE
XCM ECC KZ(8).GT.0 SUBSYS
nbody0(1NEMO)
, runbody2(1NEMO)
, snapshot(5NEMO)
, u3tos(1NEMO)
,
stou4(1NEMO)
$NEMO/src/nbody/evolve/aarseth/nbody1 nbody code
$NEMO/src/nbody/evolve/aarseth/tools various tools code
$outdir/fort.1 restart dump (compile time dep. size)
$outdir/fort.2 restart dump (compile time dep. size)
$outdir/fort.4 restart dump (compile time dep. size)
(see stou4(1NEMO) and u4tos(1NEMO))
$outdir/fort.7 formatted frame files (option KZ(7))
$outdir/OUT3 particle dump (see u3tos(1NEMO))
Peter Teuben
4-mar-98 V1.1 documented, and changed out= to outdir=, n= to nbody= PJT
17-mar-04 V1.1a fixed bug when in= was specified
17-mar-06 V1.2 using fullname for in=
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