added CITATION, iops, and updated readme accordingly

CITATION.cff

@@ -0,0 +1,27 @@
+# This CITATION.cff file was generated with cffinit.
+# Visit https://bit.ly/cffinit to generate yours today!
+
+cff-version: 1.2.0
+title: iMCRT
+message: >-
+  If you use this software, please cite it using the
+  metadata from this file.
+type: software
+authors:
+  - given-names: Matthew
+    family-names: Cooper
+    name-particle: G.
+    orcid: 'https://orcid.org/0000-0002-0165-209X'
+identifiers:
+  - type: doi
+    value: 10.5281/zenodo.4827783
+    description: The DOI for version 1.1.0 of the software
+repository-code: 'https://github.com/mgcooper/imcrt'
+url: 'https://github.com/mgcooper/imcrt'
+keywords:
+  - radiative transfer
+  - monte carlo
+  - glacier ice
+license: MIT
+version: 1.1.0
+date-released: '2021-05-21'

README.md

@@ -4,7 +4,9 @@
 
 ice Monte Carlo Radiative Transfer.  
 
-Runs on Matlab and Octave.
+## Dependencies
+
+A working installation of Matlab or GNU Octave. Confirmed to run on Matlab R2020b and Octave 7.2.0, but it should run on any recent release, and there should not be any toolbox dependencies.
 
 ## Install
 
@@ -14,16 +16,34 @@ Run `Setup.m`. If running in Octave, check `.octaverc`.
 
 Run `mcrt_verify.m` to verify model accuracy. There are three simulations that compare model output with van De Hulst's tabulated solutions to the transfer equation. It could easily be modified for a different problem by setting the inherent optical properties and geometry to new values.
 
-The `examples` directory includes code needed to reproduce the detector interference simulations reported in the paper below. If you wanted to investigate the influence of an instrument on optical measurements, that code would be a good place to start (e.g. see rodintersect.m)
+The `examples` directory includes code needed to reproduce the detector interference simulations reported in the paper below. If you wanted to investigate the influence of an instrument on optical measurements, that code would be a good place to start (e.g. see `rodintersect.m`).
+
+For general use, there is a library of "inherent optical properties" (scattering and absorption coefficients) for water ice Ih saved in `dat/mie_iops_dE.mat`. The prefix `mie_` refers to the Mie scattering formulas used to compute the scattering coefficients. The suffix `_dE` refers to the "delta Eddington" approximation used to compute the extinction coefficients: $c=\sqrt{3ab_e}$ with extinction coefficient $c$, absorption coefficient $a$, and effective (or 'reduced') scattering coefficient $b_e$. Note that this equation is identical to the diffusion approximation, where $c$ is sometimes called the "propagation coefficient". It's inverse $1/c$ is the "transport length". See `doc/tc-2020-53-supplement.pdf` for more details on how these values enter into the Monte Carlo model. In addition, `dat/ssa_iops_dE.mat` contains the same values of absorption coefficient, but values of scattering and extinction coefficient computed with the "specific surface area" approximation, which is also called the "geometric optics" approximation. This approximation is valid for scatterers about the same size or slightly larger than the interacting wavelengths. The effective particle radii are saved in the libary as well.
 
-## Reference
+## How do I cite this?
 
-If you find this model useful, please consider citing the following paper:
+If you find this model useful, please consider citing the software release (see `CITATION.cff`), and/or the following paper:
 
 Cooper, M.G., Smith, L.C., Rennermalm, A.K., Tedesco, M., Muthyala, R., Leidman, S.Z., Moustafa, S.E., Fayne, J.V., 2021. Spectral attenuation coefficients from measurements of light transmission in bare ice on the Greenland Ice Sheet. The Cryosphere 15, 1931–1953. https://doi.org/10.5194/tc-15-1931-2021
-## More
 
-The model roughly implements the one described in Wang et al. (1995). It is not meant to be an exact implementation. The model simulates transfer through a uniform slab. See doc/supplement.pdf and the two references for technical descriptions.
+    @article{cooper_2021_TC,
+      title = {Spectral Attenuation Coefficients from Measurements of Light Transmission in Bare Ice on the {{Greenland Ice Sheet}}},
+      author = {Cooper, M. G. and Smith, Laurence C. and Rennermalm, {\AA}sa K. and Tedesco, Marco and Muthyala, Rohi and Leidman, Sasha Z. and Moustafa, Samiah E. and Fayne, Jessica V.},
+      year = {2021},
+      month = apr,
+      journal = {The Cryosphere},
+      volume = {15},
+      number = {4},
+      pages = {1931--1953},
+      publisher = {{Copernicus GmbH}},
+      issn = {1994-0416},
+      doi = {10.5194/tc-15-1931-2021},
+      langid = {english}
+    }
+
+## More details
+
+The model roughly implements the one described in Wang et al. (1995). It is not meant to be an exact implementation. The model simulates transfer through a uniform slab. See `doc/tc-2020-53-supplement.pdf` and the two references for technical descriptions.
 
 Wang, L., Jacques, S. L. and Zheng, L.: MCML?Monte Carlo modeling of light transport in multi layered tissues, Computer Methods and Programs
 in Biomedicine, 47(2), 131?146, https://doi.org/10.1016/0169 2607(95)01640 F, 1995.