J an 2 00 6 Configuration Interaction calculations of positron binding to Be ( 3 P o )
The Configuration Interaction method is applied to investigate the possibility of positron binding to the metastable beryllium (1s22s2p 3Po) state. The largest calculation obtained an estimated energy that was unstable by 0.00014 Hartree with respect to the Ps + Be+(2s) lowest dissociation channel. It is likely that positron binding to parent states with non-zero angular momentum is inhibited by centrifugal barriers.
Convergence of the Partial Wave Expansion of the He Ground State
The configuration interaction (Cl) method, using a very large Laguerre orbital basis, is applied to the calculation of the He ground state. The largest calculations included a minimum of 35 radial orbitals for each l ranging from 0 to 12, resulting in basis sets in excess of 400 orbitals. The convergence of the energy and electron-electron delta-function with respect to J (the maximum angular momenta of the orbitals included in the CI expansion) were investigated in detail. Extrapolations to the limit of infinite angular momentum using expansions of the type Delta X-J = A(X)[J + 1/2](-p) + B-X[J + 1/2](-mu-1) +..., gave an energy accurate to 10(-7) Hartree and a value of accurate to about 0.5%. Improved estimates of and , accurate to 10(-8) Hartree and 0.01%, respectively, were obtained when extrapolations to an infinite radial basis were done prior to the determination of the J -> infinity limit. Round-off errors were the main impediment to achieving even higher precision, since determination of the radial and angular limits required the manipulation of very small energy and differences.
Image Projection in Immersive 3D Visualization Laboratory
In recent years, many centers in the world attempted to build a virtual reality laboratory. The main idea of such laboratory is to allow the user to “immerse” into and move in a computer-generated virtual world. In the paper, the underlying principles of the system of virtual reality (VR) are described. The selected implementations constructed by the research centers of the world are also presented. The cave automatic virtual environment (CAVE) installation is planned to be implemented at the Gdansk University of Technology. In this solution, the images will be projected on flat screens arranged in the form of a cube. The user will be located inside a transparent sphere freely rotating inside a cube, which allows simulation of free movement without changing the position of the screens. A walking motion of the user will trigger changes in the computer-generated images on screens surrounding the sphere thus creating an illusion of motion. The problems of visualization in the planned installation are outlined and discussed.