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RESEARCH

Hardware Computational Resources

Dawning Intel Xeon dual quad-core high performance workstations (Fig. 1)
Lenovo Intel Xeon dual hexa-core high performance workstations (Fig. 2)
Dawning Intel Xeon dual hexa-core high performance workstations (Fig. 1)
Pentium (R) Dual-Core high performance PCs

Fig. 1. Dawning I450 (E5504 Xeon/6GB/500GB SATA) Fig. 2. Lenovo T350 G7 (X5650 Xeon/12GB/146GB SAS)

Software Computational Resources

VASP

The commercial software subscribed in our group (see http://cms.mpi.univie.ac.at/vasp/) is a package for performing ab-initio quantum-mechanical molecular dynamics (MD) using pseudopotentials and a plane wave basis set. The approach implemented in VASP is based on a 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-step using efficient matrix diagonalization schemes and an efficient Pulay mixing. These techniques avoid all problems 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 using ultrasoft Vanderbilt pseudopotentials (US-PP) or the projector augmented wave method (PAW). Both techniques allow a considerable reduction of the necessary number of plane-waves per atom for transition me[ant]tals and first row elements. Forces and stress can be easily calculated with VASP and used to relax atoms into their instantaneous groundstate.

SIESTA

SIESTA is both a method and its computer program implementation, to perform efficient electronic structure calculations and ab initio molecular dynamics simulations of molecules and solids. SIESTA's efficiency stems from the use of strictly localized basis sets and from the implementation of linear-scaling algorithms which can be applied to suitable systems. A very important feature of the code is that its accuracy and cost can be tuned in a wide range, from quick exploratory calculations to highly accurate simulations matching the quality of other approaches, such as plane-wave and all-electron methods.

The possibility of treating large systems with some first-principles electronic-structure methods has opened up new opportunities in many disciplines. The SIESTA program is distributed freely to academics and has become quite popular, being increasingly used by researchers in geosciences, biology, and engineering (apart from those in its natural habitat of materials physics and chemistry). Currently there are several thousand users all over the world, and the paper describing the method (J. Phys. Cond. Matt. 14, 2745 (2002)) has had nearly 3000 citations.