Estimation of Gas Properties from the Lennard-Jones Potential R package chapensk version 0.5 Calculation of gas transport properties (viscosity, diffusion, thermal conductivity) using Chapman-Enskok theory (Chapman 1918, <doi:10.1098/rsta.1918.0005>) and of the second virial coefficient (Vargas et al. 2001, <doi:10.1016/s0378-4371(00)00362-9>) using the Lennard-Jones (12-6) potential. Up to the third order correction is taken into account for viscosity and thermal conductivity. It is also possible to calculate the binary diffusion coefficients of polar and non-polar gases in non-polar bath gases (Brown et al. 2011, <doi:10.1016/j.pecs.2010.12.001>). 16 collision integrals are calculated with four digit accuracy over the reduced temperature range [0.3, 400] using an interpolation function of Kim and Monroe (2014, <doi:10.1016/j.jcp.2014.05.018>). Software Depends: R (>= 2.12.0), methods, Bessel Stefan Langenberg <langenberg@uni-bonn.de> Comprehensive R Archive Network (CRAN) Stefan Langenberg [aut, cre] (ORCID: <https://orcid.org/0000-0001-5817-5469>) GPL-3 2026-06-04 application/tgz https://CRAN.R-project.org/package=chapensk doi:10.32614/CRAN.package.chapensk