Thermal desorption is a phenomenon ubiquitous in surface science. Much research has been done recently to elucidate the energetics of this process and how they are related to surface structure (i.e. varying crystallographic planes) and adsorbate coverage for various molecules. Studies of alkane desorption from the basal plane of graphite show a prefactor that is constant with chain length for longer alkane molecules [1], while experiments of shorter alkane chains on MgO(100) [2], Pt(001), and the basal plane of graphite [3] show a prefactor that increases with increasing chain length. We developed an accelerated molecular dynamics (MD) scheme to simulate thermal desorption of alkanes from the basal plane of graphite at experimentally relevant temperatures. In the framework of hyperdynamics, two different bias potentials are used to accelerate desorption. The alkanes, which range in size from pentane to hexadecane, span the range of those studied experimentally. We utilize an all-atom model for the alkane molecules. Transition-state theory is used to determine rate constants for desorption. From these rate constants, desorption energies and prefactors are determined from an Arrhenius plot. Our results from simulations of single molecules [4] provide an explanation for the chain-length dependence of alkane desorption. This explanation is based on internal degrees of freedom that are activated in the longer alkane molecules but not in the shorter alkane chains. We also examine the role of coverage in alkane desorption energetics by looking at the desorption of pentane at varying coverage. We find that rates may differ by orders of magnitude depending on the structure and coverage of the pentane film. We incorporate these coverage-dependent rates into simulations of temperature-programmed desorption (TPD) spectra and analyze them using the protocol employed in experimental studies. By comparing simulated rates as a function of coverage to those from simulated TPD spectra, we discern the implications they have for the interpretation of TPD data. [1] K.R. Paserba and A.J. Gellman, J. Chem. Phys. 115, 6737 (2001). [2] S.L. Tait et al., J. Chem. Phys. 122, 164707 (2005). [3] S.L. Tait et al., J. Chem. Phys. 125, 234308 (2006). [4] K.E. Becker and K.A. Fichthorn, J. Chem. Phys. 125, 184706 (2006).