rrlvl files in CHIANTI version 11

[Colin]

Hi all, thank you for allowing me to join this group and for the useful code and database. 

I have recently found CHIANTI because I am looking for a way to calculate rate coefficients for radiative recombination between singly ionized atomic species (primarily O and N) and electrons, meaning I am interested in for example 

NII + e --> NI + photon

What I need are rate coefficients for radiative recombination reactions that result in the neutral atom being in different excited states. I will always assume the ion reactant is in the ground state. Ideally I would have electron energy dependent crosssections for all these reactions but I am not currently in a position to be picky and rates would also be fine. 

This brought me to ChiantiPy and after obtaining it and getting the data tarball, I tried creating an Ion object and simply outputting RrlvlRate, e.g.

import ChiantiPy.core as ch

ion = ch.ion('n_2', temperature=100, setup=True) 

ion.rrRate()

ion.rrlvlDescale()

print(ion.RrlvlRate)

I am not sure how much of this is necessary but after some trail-and-error and inspection of the Ion class I felt like I needed to run rrRate and rrlvlDescale. The output that I get is "{'rate': array([0])}". The fundamental problem appears to be that it looks for rrlvl files for the species I am interested in but they do not exist, i.e. there is no 'CHIANTI_11.0_database/n/n_2/n_2.rrlvl'.

I would be very grateful if anybody could let me know where I am going wrong here or if there is a better source for this information. Thanks in advance.  

[Roger Dufresne]

Hi Colin,

Thanks for asking about the files. The .rrlvl files are used to calculate the X-ray satellite lines, mostly for Li- and He-like ions. The ions you are looking for are low charge and the files are not available in CHIANTI. However, the original data comes from the APAP network (www.apap-network.org) and data for many ions are publicly available online. 

For the rate coefficients you need the files stored at https://www.apap-network.org/DATA_AS/RR/. They are fully resolved by initial metastable levels and all final levels in the model. Otherwise, if you want cross sections you will need the photo-ionisation cross sections located here https://www.apap-network.org/DATA_AS/PI/. The latter will not give you the total RR rates into the ion because recombination into high n states is important and that is only available in the rate coefficient files.

For N II combining into N I, for example, you will need to follow the link to the C-like files (https://www.apap-network.org/DATA_AS/RR/RR_web/adf48/clike/) and there you will find two rate coefficients files for N, one in LS-coupling and the other in intermediate coupling. 

There are keys on the website for deciphering the file names and formats, but I am happy for you to contact me directly if you need more help deciphering the files.

Best wishes,

Roger Dufresne.

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From: chi...@googlegroups.com <chi...@googlegroups.com> on behalf of Colin <colinjo...@gmail.com>
Sent: Monday, March 3, 2025 12:17 PM
To: chianti <chi...@googlegroups.com>
Subject: rrlvl files in CHIANTI version 11

 

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[Ken Dere]

I think that the data you are looking for are in the xx.rrcoeffs files.

these are similar to the xx.rrlvl files except that they contain rates between more levels.  The xx.rrlvl files only contain rates from ground level to ground level.

if you are willing to do some Python programing, the util.io.rrlvlRead function can be modified to read these files.  Also the ion.rrlvlDescale can be modified to scale the parameters in the xx.rrcoeffs files.

I am in the process of doing that now but my time is a bit limited right now.

Ken

[Roger Dufresne]

Hi everyone,

The .rrcoeffs files are new to CHIANTI v.11 released a few months ago. They are used solely for the advanced models that calculate density dependent effects on the ion fractions.

The .rrcoeffs files are like the .rrparams files. The .rrparams files hold the fitting coefficients used to calculate the total RR rate from the ground level of the recombining ion. They are not resolved by the individual levels in the final recombined ion. The .rrcoeffs files hold the same information as this, but they also include the fitting coefficients for total RR rates from the metastable levels of the recombining ion. The rates from each initial level are the rates totalled over all states in the final, recombined ion.

I believe Colin wants the files that list the individual RR rates from the ground level of the recombining ion into each state of the final ion. I understand that rates of these types are stored in the .rrlvl files. If this is the case, the .rrlvl files are only present for selected ions from the He-like and Li-like sequences. Any other data would need to be processed from the original data files on the APAP website. I have been processing a number of these files recently for my own use, and so I can offer help if Colin needs to process the APAP data.

I hope I have understood this correctly, but please let me know if I am misunderstanding something.

Best wishes,

Roger.

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[Colin]

Hi all, thanks for the useful information.

 I have been overwhelmed with some work in my day job so I have not had time to look into this since posting the original question but I try to do it now. Roger is right that I need rates from the ground level of the recombining ion into each state of the final ion and in a couple of cases (OII and NII) also from one of the excited states of the recombining ion. The aim is to include this in a more detailed model for planetary upper atmospheres that I developed a while ago in order to better determine the populations of the excited states of atomic species since this is important for determining both cooling and heating. I'll let you know how I get on with parsing the APAP files.  

Best,

Colin