Implementing and evaluating a fictitious electron dynamics method for the calculation of electronic structure: Application to the Si(100) surface

A density matrix based fictitious electron dynamics method for calculating electronic structure has been implemented within a semi-empirical quantum chemistry environment. This method uses an equation of motion that implicitly ensures the idempotency constraint on the density matrix. Test calculations showed that this method has potential of being combined with simultaneous atomic dynamics, in analogy to the popular Car-Parrinello method. In addition, the sparsity of the density matrix and the sophisticated though flexible way of ensuring idempotency conservation while integrating the equation of motion creates the potential of developing a fast linear scaling method.