Simple notice for non astronomers:

THE INPUT FILES YOU MAY BE INTERESTED IN: 

- osu.2005 is the list of reactions. The first three columns represent the 
reactants. The next four columns are the products. The three next numbers 
are used to calculate the rate coefficient of the reaction.  
The next column is the type of the reaction:
 0 Gas-grain interaction, Electron-grain recombination
 1 Cosmic-ray ionization (direct process)
   Cosmic-ray induced photoreactions (indirect process)
 2 Ion-molecule reactions, Charge exchange reactions
 3 Negative ion - neutral species reactions
 4 Radiative association
5 Associative ejection
 6 Neutral + Neutral -> ion + electron (only one reaction)
 7 Neutral-Neutral chemical reactions
 8 Neutral-Neutral radiative association
 9 Dissociative recombination
10 Radiative recombination
 11 Positive ion - Negative ion recombination
 12 Electron attachment
 13 Photo-ionization, Photo-dissociation
- cond_initial.dat is the list of species with their initial abundances 
(with respect to total H)
- input_parameter.dat contains the model parameters (such as temperature and
density)

THE WAY THE RATE COEFFICIENTS ARE COMPUTED DEPENDING ON THE TYPE: 

A, B and C are the three first numbers of each reaction line.
ITYPE = 0 : k = A * (T/300)^B * H-total-density 
where T = temperature 
The calculation of H2 formation has been modified compared to 
Leung et al. ApJS 1984, 56, 231 to decrease the statistical noise of the 
computer calculation.

ITYPE = 1 : k = A * ZETA 
where ZETA = total H2 ionization rate, usually 1.3e-17s-1 is used.

ITYPE = 2-12 : k = A * (T/300)^B * exp(-C/T)

ITYPE = 13 : k = A * exp(-C * Av)
where Av = visual extinction of the cloud related to the total H density 
by the approximation Av= H-density / 1.6E21
	 
	 
TO COMPILE AND RUN THE MODEL:

g77 -c nahoon.f
g77 -c dlsode.f
g77 -o nahoon nahoon.o dlsode.o
nahoon or ./nahoon depending on the system you are using

THE OUTPUT FILES YOU MAY BE INTERESTED IN:

- Kout.dat contains the rate coefficients calculated at the given température.
- plot.dat contains the abundance species at specific times.
	 
IF YOU WANT TO TEST THE EFFECT OF A RATE COEFFICIENT:	 
	 
1) Save the initial chemical database and the plot.dat file for reference.

2) Edit the file osu.2005.

3) Add the reaction at the end of the file with the correct format.

4) Be sure to use the correct type of reaction in column 11, the number in column 12 
is not important (put 000), be sure to put the right number in column 13 (previous line+1) 
and to put a number in the last column for the uncertainty factor even if it is a dummy number.

5) Edit the nahoon.f file

6) Change NRTOT=4423 1 time in nahoon.f by the total number of reactions.

7) Change NRBIS2=4423 4 times in nahoon.f. 

8) Compile again the nahoon.f file and run the model:
g77 -c nahoon.f
g77 -o nahoon nahoon.o dlsode.o
nahoon or ./nahoon depending on the system you are using

9) You can compare the new plot.dat file with the previous one.