Molpop-CEP is a code for exact solution of the radiative transfer problem in multi-level atomic systems. The novel contribution of the code is that the radiative transfer equation is analytically integrated so that the final problem is reduced to the solution of a non-linear algebraic system of equations in the level populations. The radiative transfer is solved using the Coupled Escape Probability formalism presented by Elitzur & Asensio Ramos (2006) and summarized in the last chapter of the manual present below. The current version of the code is limited to plane-parallel slabs with arbitrary spatial variations of the physical conditions.

The code is written in standard Fortran 90. It can solve all problems involving 1D plane-parallel media with arbitrary atoms/molecules since all radiative and collisional information is given as external files. The code is distributed with a database of atomic/molecular information but the user can provide additional input for new species. In addition to the exact calculation, Molpop-CEP allows the user to compute solutions using the standard single-zone escape probability and LVG approximations. Line overlap can be also taken into account in this case. As output, the code generates standard information on user-selected lines.


Molpop-CEP can be downloaded here. You will be redirected to the Github repository, where we keep the latest version of the code. You can download it by clicking on the "Download ZIP" button or using 'git clone'. Follow the steps in the manual after decompressing the file to compile the code. You will need a Fortran 90 compiler (either Intel Fortran or GFortran).

This code is copyrighted, 1976-2014 by Moshe Elitzur and Andrés Asensio Ramos, and may not be copied without acknowledging its origin. Use of this code is not restricted, provided that acknowledgement is made in each publication. The bibliographic reference to this version of Molpop-CEP is Elitzur & Asensio Ramos (2006, MNRAS 365, 779). Send bug reports, comments and questions to any of the authors.


The manual that you can find inside the distribution explains all the details of the code, how to compile and make it run. It includes some sample calculations to guide the user on how to configure it.