Energy landscape of silicon systems and its description by force fields, tight binding schemes, density functional methods, and quantum Monte Carlo methods

The accuracy of the fundamental properties of the energy landscape of silicon systems obtained from density functional theory with various exchange-correlation functionals, a tight binding scheme, and force fields is studied. Depending on the application, quantum Monte Carlo or density functional theory results serve as quasiexact reference values. In addition to the well-known accuracy of density functional methods for geometric ground states and metastable configurations we find that density functional methods give a similar accuracy for transition states and thus a good overall description of the energy landscape of the silicon systems. On the other hand, force fields give a very poor description of the landscape that are in most cases too rough and contain many spurious local minima and saddle points or ones that have the wrong height.