Abstract
High precision atomic data are indispensable for studies of fundamental symmetries, tests of fundamental physics postulates, developments of atomic clocks, ultracold atom experiments, astrophysics, plasma science, and many other fields of research. We have developed a new parallel atomic structure code package that enables computations that were not previously possible due to system complexity. This code package also allows much quicker computations to be run with higher accuracy for simple systems. We explored different methods of load-balancing matrix element calculations for many-electron systems, which are very difficult due to the intrinsic nature of the computational methods used to calculate them. Furthermore, dynamic memory allocation and MPI parallelization have been implemented to optimize and accelerate the computations. We have achieved near-perfect linear scalability and efficiency with the number of processors used for calculation, paving the way towards the future where most open-shell systems will finally be able to be treated with good accuracy. We present several examples illustrating new capabilities of the newly developed codes, specifically correlating up to all 60 electrons in the highly charged Ir17+ ion and predicting certain properties of Fe16+.
Highlights
Studies of the fundamental symmetries with atoms and ions require knowledge of atomic properties as well as calculations to extract potential new physics from the experiments [1]
The speedup achieved with the parallel configuration interaction (CI)+perturbation theory (PT) program and the parallel matrix element program is very similar, with the parallel Configurations with Valence Perturbation Theory (CI+PT) program averaging around 75–85% efficiency and the parallel matrix element program averaging around 80–90% efficiency with the number of cores
We have developed a new parallel atomic structure code package that has opened a lot of new possibilities for high-precision calculations of atomic properties of various complex many-electron systems
Summary
Studies of the fundamental symmetries with atoms and ions require knowledge of atomic properties as well as calculations to extract potential new physics from the experiments [1]. In the framework of the CI method, only valence–valence interactions are treated explicitly, while core excitations are neglected This essentially limits the accuracy of the method when it is applied to a heavy many-electron atom or ion. They used an idea that a CI method treats the interactions between valence electrons, while MBPT can be effectively used to account for core–core and core–valence correlations Combining these two methods, it is possible to acquire benefits from both approaches and attain higher computational accuracy. The inclusion of the all-order method which provides accurate solutions for a large number of properties of atoms and ions with up to 5–6 valence electrons has been completed and made fully compatible with this code package.
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