Positron States in Materials: Dft and Qmc Studies
نویسنده
چکیده
Abstract First-principles approaches based on density functional theory (DFT) for calculating positron states and annihilation characteristics in condensed matter are presented. The treatment of electron-positron correlation effects is shown to play a crucial role when calculating affinities and annihilation rates. A generalized gradient approximation (GGA) takes the strong inhomogeneities of the electron density into account and is particularly successful in describing positron characteristics in various materials such as metals, semiconductors, cuprate superconductors and molecular crystals. The purpose of Quantum Monte Carlo (QMC) simulations is to provide highly accurate benchmark results for positron-electron systems. In particular, a very efficient QMC technique, based on the Stochastic Gradient Approximation (SGA), can been used to calculate electron-positron correlation energies.
منابع مشابه
Investigation of a Quantum Monte Carlo Protocol To Achieve High Accuracy and High-Throughput Materials Formation Energies.
High-throughput calculations based on density functional theory (DFT) methods have been widely implemented in the scientific community. However, depending on both the properties of interest as well as particular chemical/structural phase space, accuracy even for correct trends remains a key challenge for DFT. In this work, we evaluate the use of quantum Monte Carlo (QMC) to calculate material f...
متن کاملQuantum Monte Carlo, density functional theory, and pair potential studies of solid neon
We report quantum Monte Carlo QMC , plane-wave density-functional theory DFT , and interatomic pair-potential calculations of the zero-temperature equation of state EOS of solid neon. We find that the DFT EOS depends strongly on the choice of exchange-correlation functional, whereas the QMC EOS is extremely close to both the experimental EOS and the EOS obtained using the best semiempirical pai...
متن کاملSCIENTIFIC HIGHLIGHT OF THE MONTH Petascale computing opens new vistas for quantum Monte Carlo
For many kinds of problem the accuracy of quantum Monte Carlo (QMC) is much better than that of density functional theory (DFT), and its scaling with number of atoms is much more favourable than that of high-level quantum chemistry. However, the widespread use of QMC has been hindered by the fact that it is considerably more expensive than DFT. We show here that QMC is very well placed to explo...
متن کاملPetascale computing opens new vistas for quantum Monte Carlo
For many kinds of problem the accuracy of quantum Monte Carlo (QMC) is much better than that of density functional theory (DFT), and its scaling with number of atoms is much more favourable than that of high-level quantum chemistry. However, the widespread use of QMC has been hindered by the fact that it is considerably more expensive than DFT. We show here that QMC is very well placed to explo...
متن کاملQuantum Monte Carlo computations of phase stability, equations of state, and elasticity of high-pressure silica.
Silica (SiO(2)) is an abundant component of the Earth whose crystalline polymorphs play key roles in its structure and dynamics. First principle density functional theory (DFT) methods have often been used to accurately predict properties of silicates, but fundamental failures occur. Such failures occur even in silica, the simplest silicate, and understanding pure silica is a prerequisite to un...
متن کامل