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VASP is a complex package for performing ab-initio quantum-mechanical molecular dynamics (MD) simulations using pseudopotentials or the projector-augmentedwave method and a plane wave basis set. The approach implemented in VASP is based on the (finite-temperature)local-density approximation with the free energy as variational quantity andan exact evaluation of the instantaneous electronic ground state at each MD time step. VASP uses efficient matrix diagonalisation schemesand an efficient Pulay/Broyden charge density mixing.These techniques avoid all problems possibly occurring in the original Car-Parrinello method,which is based on the simultaneous integration of electronic and ionicequations of motion.The interaction between ions and electrons is described by ultra-softVanderbilt pseudopotentials (US-PP) or by the projector-augmentedwave (PAW) method.US-PP (and the PAW method) allow for a considerablereduction of the number of plane-waves per atom fortransition metals and first row elements.Forces and the full stress tensor can be calculated with VASP and used to relaxatoms into their instantaneous ground-state.