Data sets associated with static and dynamic density functional calculations are reported for the four known polymorphs of l-cysteine and for models associated with the known disorder in Form I.. Static calculations are used to explore the relative free energies (within the harmonic approximation) of the polymorphs as a function of pressure. The energetics for dihedral angle rotation are explored and the barriers for rotation between the hydrogen bonding motifs have been calculated for each polymorph. Molecular dynamics calculations are reported for each polymorph and for models of hydrogen bond disorder which are known to exist at higher temperatures. Finally static and dynamic calculations of the infrared and terahertz spectra are performed.