DATAFILES ######### Pure gas-phase models include reactions up to ITYPE = 13 (see Itype.txt for a description). For models with surface chemistry, additional processes with corresponding itypes are incorporated: ITYPE PROCESS 14 grain surface reactions 15 thermal evaporation 16 cosmic ray-induced desorption 17 photodissociation due to cosmic ray-induced photons 18 photodissociation due to cosmic ray-induced photons 19 photodissociation due to external photons 20 photodissociation due to external photons 99 dummy freeze-out terms JC JC JC2 1.86E+03 0.00E+00 0.00E+0014 1 *4219* ^^ - here is where the itype number is displayed in jcddata The main datafiles are as follows: 1, from Paper 1 - no surface photochemistry jcddata00.1pc0 M1/A 'slow H' jcddata00.1hpc0 M1/B jcddata00.2pc0 M2/A 'slow all' jcddata00.2hpc0 M2/B 2, from Paper 2 - with surface photochemistry jcddata00.1 P1/A jcddata00.1h P1/B jcddata00.2 P2/A jcddata00.2h P2/B where /A => case A abundances used, i.e. H2 rich /B => case B abundances used, i.e. H rich These files are for the 'standard' physical conditions of: nh=xnt0=2.000e+04 T=temp0=1.000e+01 Av=tau0=1.000e+01 The surface reaction rates (itype 14) depend on density (nh), temperature (T) and the species desorption (ED) and diffusion (Eb) barriers. The thermal evaporation and cosmic ray-induced desorption terms are also temperature and desorption barrier dependent. The main progams with which we run the models (jchnsmc.00.m1.mod1.f & jchnsmc.00.m2.mod1.f) automatically rescale the surface rxn rates (itype 14) for the density used in the jcddata file. Therefore, one can simply use the datafiles above to explore density and Av dependence. However, since the calculation of temperature dependence is much more complex, in order to explore the sensitivity of model results on temperature, one must construct new jcddata files. I have version of the above datafiles for different temperatures. Labelling used is: jcddata00.1.11k jcddata00.2.pc0.15k Temp range currently available: 10 - 15 K for M1 & P1 10 - 20 K for M2 & P2 (NB: Tammay has models up to 35-50K available) Photochemistry parameters: @@@@@@@@@@@@@@@@@@@@@@@@@@ If you do not want to use surface pchem, all the following parameters should be set to 0.0 (as is done in the 'pc0' jcddata files), *except* for: uvgas which is for itype13 -> the g-p pdis terms ^^^^^ this should be at 1.0, unless you are scaling the external photon field. cra = scale for CR photons on to grains (itype 17) crb = scale for CR photons on to grains (itype 18) uvgra = scale for external photons on to grains (itype 19 & 20) set the above 3 terms to 1.0 for surface pchem, or a value >0 if scaling the surface pchem rates pmonlay = number of monolayers that you are allowing to undergo surface pchem (in terms of absolute concentration) NOTE: The value of pmonlay depends on the density used. For nh=2.00e+04, pmonlay = 2.66e-02 for 1 monolayer pmonlay = 2.66e+00 for 100 monolayers For nh=1.00e+03 pmonlay = 1.33e-03 for 1 monolayer pmonlay = 1.33e-01 for 100 monolayers How to calc pmonlay: 1 monolayer = 10^6 molecules (since there are 10^6 binding sites per grain) absolute concentration of a surface species = no. mol * n_d n_d = 1.33e-12 * n_H pmonlay(1 mono) = 1.33e-06 * n_H pmonlay(100 mono) = 1.33e-04 * n_H Note, these jcddata00.1 & 00.2 files are for the Olivine surface. Amorphous Carbon Surface Models ******************************* Models 3 (M3 & P3) and 4 (M4 & P4) are for an amorphous carbon surface. All the desorption barriers are scaled from their values in M1 and M2 by 1.7 - this is the value of the ratio between ED for olivine and a.c. measured by Katz et al (1999). In M3, H is slowed in a similar way to M1, whereas in M4 the full barrier is adopted. These are labelled: jcddata00.m3pc0.18k jcddata00.m3pc0.20k jcddata00.m4pc0.18k jcddata00.m4pc0.20k jcddata00.m3.18k jcddata00.m3.20k jcddata00.m4.18k jcddata00.m4.20k dpr 8/3/00