Hybrid avenues within the SIESTA project
The SIESTA method for linear scaling density functional calculations offers various possibilities of interaction with other simulation approaches. Based on atomic orbitals of finite support, it naturally bridges between the plane-wave and the tight-binding methods. The level of theory within the method is wide as well, from Harris-functional based minimal basis quick simulations to quite converged DFT calculations. After a brief introduction to the method, the ongoing related hybrid projects will be outlined, both intra-siesta (for both size and time scales), and with other techniques, from empirical models (springs for efficient relaxations, ONIOM) on one side, to heavier DFT approaches (CONQUEST) on the other. An important aspect of our hybrid projects and of hybrid models in general is code interoperability, both from the point of view of data transfer as of code integration. Our efforts in this direction will be also presented.