Hidekazu Tomono

GPU based acceleration of first principles calculation

We present a Graphics Processing Unit (GPU) accelerated simulations of first principles electronic structure calculations. The FFT, which is the most time-consuming part, is about 10 times accelerated. As the result, the total computation time of a first principles calculation is reduced to 15 percent of that of the CPU.

Dynamic Correlation between Superionic Coppers in α-CuI

We determine the instantaneous and simultaneous occupancy sites of the superionic coppers in α-CuI by means of the first principles molecular dynamics method. The coppers are located at incommensurate sites in the periodic lattice potential. The covalent bonds exist between the nearest coppers and between the copper and its nearest iodine. The formation of the dynamic dimers is the origin of the conduction. The ionicities of the atoms depend on their locations. The average ionicities are Cu +0.28 and I -0.28 . The incomplete electron transfer enables the atoms to form the covalent bonds between them. The superionic conductor α-CuI is an intermediate electronic state between the ionic sodium chloride crystal and the covalent bonded zinc blend crystal with respect to both the ionicities and the average locations of the coppers.

Electron Transfer from Hydrogen Molecule to Au(111) During Dissociative Adsorption: A First-Principles Study

We investigate the electron transfer from a dissociatively adsorbed H 2 molecule to a Au(111) surface using the first-principles methods. A fractional electron transfers from a molecule to a substrate, and potential energy increases during the process. The initial energy increase coincides with that of the isolated, separated, and positively charged H 2 molecule calculated by the real-space density functional method. The barrier formation is due to the destabilization of the molecule induced by the electron transfer. The electronegativity difference between the adsorbate and the substrate determines the direction of the electron transfer.

Acceleration of orbital-free first principles calculation with graphics processing unit GPU

Computational material design requires efficient algorithms and high-speed computers for calculating and predicting material properties. The orbital-free first principles calculation (OF-FPC) method, which is a tool for calculating and designing material properties, is an O(N) method and is suitable for large-scaled systems. The stagnation in the development of CPU devices with high mobility of electron carriers has driven the development of parallel computing and the production of CPU devices with finer spaced wiring. We, for the first time, propose another method to accelerate the computation using Graphics Processing Unit (GPU). The implementation of the Fast Fourier Transform (CUFFT) library that uses GPU, into our in-house OF-FPC code, reduces the computation time to half of that of the CPU.