The method for the paper that is quoted in the Wikipedia article can be found starting on page 2 (the full text is available for free): http://iopscience.iop.or

The method for the paper that is quoted in the Wikipedia article can be found starting on page 2 (the full text is available for free): http://iopscience.iop.org/article/10.1088/1748-9326/10/11/114005/pdf http://iopscience.iop.org/article/10.1088/1748-9326/10/11/11.... It's three and a half pages long and includes many citations to other published articles.