This is the file .par that controls the behavior of GRASIL. 

The file consists of several sections, which can appear in any order and
begins with a line consisting only in one of the following keywords.

- MAIN: section devoted mostly to model parameters, such as those for the
geometry of the galaxy;
- SPECTRA: directions of required SEDs;
- SSP: names of files containing SSPs;
- MIXDIF: parameters specifying the dust mixture to be used for the diffuse
component;
- MIXMOL: parameters specifying the dust mixture to be used for molecular
clouds;

Some of these sections (MAIN, MIXDIF and MIXMOL) are 'free form', in the sense
that their parameters can appear in any order, each one on a different line of
the file. The line contains the name of the parameter in the first ten
columns, its value from column 11 to column 20, and the rest of the line is
left for comments. In addition, each line starting with %, # or a blank space
is ignored, and can be used for longer comments. The other sections are
instead fixed form and their structure (order of lines, order of parameters in
line, number of comment lines, etc..) can't be changed.

The typical user often modifies section MAIN, sometimes SPECTRA and SSP,
but is strongly encouraged to accept MIXDIF and MIXMOL as they stand, which
means to adopt the dust mixture described in Silva, L., Granato, G.L.,
Bressan, A., Danese, L., 1998, ApJ, 509, 103.


MAIN
# This section is quite free form: parameters may appear in any order,
# lines begining with #, % or blank space are for comments, otherwise
# from column 1 to 10 an identifier of the parameter (case sensitive)
# from 11 to 20 its value (always real with explicit decimal point)
# from 21 on comments.
#2345678901234567890123456789
#

# NOTE: below each parameter the allowed range is reported within []

tgal      12.0      age of the model
# [0<tgal<maximum age in .sf file]

gastmp    1.0e-1    if igastmp=1 then gas mass is forced to 
# gastmp*(final total mass in .sf file), if igastmp=0 then gastmp is not
# used and the actual gas mass at tgal listed in .sf file is adopted
# [0<gastmp<1] 
# istarfo=0 and igastmp=1
igastmp   0.0       see gastmp
# [igastmp=0,1]

mmolfraz  0.5       fraction of molecular over total gas
# NOTE: if mmolfraz<0 no gas, useful for bare EPS
# if mmolfraz>1, then it is reset to min(1,SFR(tgal)/mmolfraz), 
# where SFR is in Msun/yr. This is used to have mmolfraz proportional to SFR.
# [mmolfraz is free, but be careful!]

mcloud    1.0e6     Mass (Msun) of molecular clouds (MCs)
# NOTE: that the SED depends on mcloud and rcloud only through their
# combination mcloud/rcloud^2, which together with dsug sets the cloud
# optical depth. 
# [1e3<mcloud<1e7] 
rcloud    10.0      radius (pc) of molecular clouds
# [1<rcloud<1000]

etastart  0.018     Gyr see below
# fraction f of SSP energy inside MCs depends on its age t according to
# f=1                        if t<=etastart
# f=1-(t-etastart)/etastart  if etastart<t<=2*etastart
# f=0                        otherwise
# [0.0001<etastart<1000.0]

flutflag  0.0       if 0.0 no computation of T fluctuations of small
# grains (speeds up a lot), if 1.0 fluctuations are computed. Usually
# in actively star-forming models fluctuations have a negligible effect
# on the global galaxy SED.
# [flutflag=0.0,1.0 usually I suggest 0.0]

idz       0.0       sets the meaning of dsug (see below)
# [idz=0.0,1.0]
dsug      1.0e-2    
# if idz=0.0 dsug is simply the dust/gas mass ratio. If idz=1.0
# dsug is the proportionality factor between Z and dust/gas.
# In this case dsug=0.45 gives the standard DL dsug=1/110 for Zsun
# [reasonable 1e-4<dsug<0.1 if idz=0.0, 0.005<dsug<5.0 if idz=1.0, but
# program checks only 1e-4<dsug<5.0]
 
tgra      400.0     maximum T of graphite grains in MCs
tsil      400.0     maximum T of silicate grains in MCs
# [100<t<2000]

igeo      1.0       sets the geometry of stars and gas
# igeo=1 King profiles: core radii given by rcstar and rcdiff
# igeo=2 Exponentials of distances from polar axis and from equator.
# scale lengths given by (rdstar,rddiff) and  (zdstar,zddiff) 
# igeo=-1 for a bulge+disk composite geometry. 
# the SF history is assigned to the 2 components according to
# bulge/total mass ratio read in file mon_name.bst ??? spiegare meglio e controllare
# [igeo -1,1,2]

rcstar    0.5       [kpc] igeo=1
rcdiff    1.0       [kpc] igeo=1
rdstar    3.0       [kpc] igeo=2
rddiff    3.0       [kpc] igeo=2
zdstar    0.5       [kpc] igeo=2
zddiff    0.5       [kpc] igeo=2
# [0.05<rc<10] [0.5<rd<100] [0.1<zd<10]

#
#
SPECTRA
Directions in degrees from the polar axis in which the SEDs are computed:
4  number of directions (suggestion: put 1 for spherical symmetric models!)
0.0  degrees
30.0 degrees
60.0 degrees
90.0 degrees
#
#
SSP
Names of SSPs to be used. List ended by a comment line
First column put 1 if ssp is to be used, 0 otherwise. 
1    'Z0001.sal'
1    'Z0004.sal'
1    'Z004.sal'
1    'Z008.sal'
1    'Z02.sal'
1    'Z05.sal'
1    'Z1.sal'
#
che_evo must be run with an IMF identical to that used to generate the SSP
files (sal=Salpeter, ken=Kennicut, sca=Scalo, msc=Miller & Scalo). The only
thing that can be (slightly) different is the lower mass limit (in the SSP it
is always 0.15), as long as the value used in che_evo affects only the
normalization (i.e. M/L) but not the shape of the SSPs.

WE SUGGEST TO LEAVE THE FOLLOWING SECTIONS AS THEY ARE!

MIXDIF
# Parameters setting the dust mixture in the diffuse component
# This section is quite free form: parameters may appear in any order,
# lines begining with #, % or blank space are for comments, otherwise
# from column 1 to 10 an identifier of the parameter (case sensitive)
# from 11 to 20 its value (always real with explicit decimal point)
# from 21 on comments.
#2345678901234567890123456789
#parameters for graphite follow  
amin_gr   0.0008e-4 minimum radius
amax_gr   0.25e-4   maximum radius
ab_gr     0.0050e-4 break radius between the two power laws
beta1_gr  -3.5      power law index from amax to ab
beta2_gr  -4.05     pawer law index from ab to amin
corgra    1.00      correction factor with respect to abundance in DL model
# can be used to vary the ratio between graphite and silicate
# parameters for silicate follow  
amin_si   0.0050e-4 minimum radius
amax_si   0.25e-4   maximum radius
ab_si     0.0003e-4 break radius between the two power laws
beta1_si  -3.5      power law index from amax to ab
beta2_si  -3.95     pawer law index from ab to amin
corsil    1.00      correction factor with respect to abundance in DL model
# can be used to vary the ratio between graphite and silicate
# parameters for PAHs follow
xx        3.03e-25  normalization power law PAHs
xh        0.2       hydro coverage PAHs
#
MIXMOL
# Parameters setting the dust mixture in the molecular clouds
# This section is quite free form: parameters may appear in any order,
# lines begining with #, % or blank space are for comments, otherwise
# from column 1 to 10 an identifier of the parameter (case sensitive)
# from 11 to 20 its value (always real with explicit decimal point)
# from 21 on comments.
#2345678901234567890123456789
#parameters for graphite follow  
amin_gr   0.0008e-4 minimum radius
amax_gr   0.25e-4   maximum radius
ab_gr     0.0050e-4 break radius between the two power laws
beta1_gr  -3.5      power law index from amax to ab
beta2_gr  -4.05     pawer law index from ab to amin
corgra    1.00      correction factor with respect to abundance in DL model
# can be used to vary the ratio between graphite and silicate
# parameters for silicate follow  
amin_si   0.0050e-4 minimum radius
amax_si   0.25e-4   maximum radius
ab_si     0.0003e-4 break radius between the two power laws
beta1_si  -3.5      power law index from amax to ab
beta2_si  -3.95     pawer law index from ab to amin
corsil    1.00      correction factor with respect to abundance in DL model
# can be used to vary the ratio between graphite and silicate
# parameters for PAHs follow
xx        3.03e-26  normalization power law PAHs
xh        0.2       hydro coverage PAHs
#
# is better to leave some comment line at the end