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Introduction

VASP is a complex package for performing ab-initio quantum-mechanical molecular dynamics (MD) simulations using pseudopotentials or the projector-augmented wave 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 and an exact evaluation of the instantaneous electronic ground state at each MD time step. VASP uses efficient matrix diagonalisation schemes and 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 ionic equations of motion. The interaction between ions and electrons is described by ultra-soft Vanderbilt pseudopotentials (US-PP) or by the projector-augmented wave (PAW) method. US-PP (and the PAW method) allow for a considerable reduction of the number of plane-waves per atom for transition metals and first row elements. Forces and the full stress tensor can be calculated with VASP and used to relax atoms into their instantaneous ground-state.

The VASP guide is written for experienced user, although even beginners might find it useful to read. The book is mainly a reference guide and explains most files and control flags implemented in the code. The book also tries to give an impression, how VASP works. However, a more complete description of the underlying algorithms can be found elsewhere. The guide continues to grow as new features are added to the code. It is therefore always possible that the version you hold in your hands is outdated. Therefore, users might find it useful to check the online version of the VASP guide from time to time, to learn about new features added to the code.

Here is a short summary of some highlights of the VASP code:


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N.B. Requests for support are to be addressed to: vasp.materialphysik@univie.ac.at