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First-principles Molecular Dynamics Study of the Time Variations of the Electronic States in Amorphous Si
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HYDROGEN-BERYLLIUM COMPLEXES IN CRYSTALLINE SILICON
No full textWe present the results of ab initio pseudopotential calculations to study the atomic structure of various forms of hydrogen-beryllium complexes in crystalline Si. For both the monatomic- and diatomic-hydrogen-Be complexes considered, the C site which corresponds to the middle of the rhombus formed by two neighboring Be-Si bonds is found to be energetically most favorable for interstitial H atoms. In a recently proposed [111]-oriented substitutional-interstitial Be pair which was shown to be more stable than a single substitutional Be, H is also positioned at the C site. For monatomic-H-Be complexes, we propose a hydrogen tunneling path going through an M site, which is located midway between two neighboring C sites, with an energy barrier of about 0.4 eV
EFFICIENT MODIFIED JACOBI RELAXATION FOR MINIMIZING THE ENERGY FUNCTIONAL
No full textWe present an efficient scheme of diagonalizing large Hamiltonian matrices in a self-consistent manner. In the framework of the preconditioned conjugate gradient minimization of the energy functional, we replace the modified Jacobi relaxation for preconditioning and use for band-by-band minimization the restricted-block Davidson algorithm, in which only the previous wave functions and the relaxation vectors are included additionally for subspace diagonalization. Our scheme is found to be comparable with the preconditioned conjugate gradient method for both large ordered and disordered Si systems, while it is more rapidly converged for systems with transition-metal elements
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