Results of the Austrian-Ceylonese hydrobiological mission 1970 of the 1st Zoological Institute of the University of Vienna (Austria) and the Department of Zoology of the University of Ceylon Vidyalankara Campus, Kelaniya (Sri Lanka). Pt. 16. the Ceylonese Trichoptera

The Trichoptera collected in Sri Lanka by the Austrian Indo-Pacific expedition in autumn and winter 1970 (larvae and adults) are evaluated systematically and ecologically. The following new species are described: Pseudoneureclipsis starmuehlneri, P. maliboda (Polycentropodidae), Oecetis belihuloya (Leptoceridae), and Helcopsyche sri lanka (Helicopsychidae). Helicopsyche ceylanica Brauer 1866 is re-described. Several types of larvae and cases of Hydropsyche (Hydropsychidae), Ceylanopsyche (Sericostomatidae) and Helicopsyche are described or at least roughly characterised. According to the larval characters the genus Ceylanopsyche seems to belong to Sericostomatidae s. str.

Annual Report of the Game and Fisheries Department for the period 1st July 1956 to 30th June, 1957

This report continues to cover the period of the financial year. Although, as before, for the sake of continuity and accuracy many of the statistics refer to the calendar year. The year has been notable in particular for the launching of extensive research projects on wild-life conservation problems, and much progress has already been made. This has been rendered possible by the greatly appreciated help and interest of the Fulbright Commission, who arranged for three experienced American wild-life scientists to work on these problems in Uganda. The latter have been working in conjunction with The Game and Fisheries Department's Biologist, as a team under the general Direction of the recently created Fauna Research Committee.

Results of the Austrian-Ceylonese hydrobiological mission 1970 of the 1st Zoological Institute University of Vienna (Austria) and the Department of Zoology of the University of Ceylon, Vidyalankara Campus, Kelaniya (Sri Lanka). Pt 17. The freshwater gastropods of Ceylon

In the present study the specimens collected by the Austrian-Ceylones hydrobiological mission 1970 are described. The freshwater gastropods in this study were collected from 100 different localities, mostly running waters, but some were also collected from stagnant waters like pools, irrigated paddy fields, swamps and water reservoirs (tanks). Listed from these localities are 31 species (and subspecies) 28 species are Streptoneura (=Prosobranchia), 3 species are Euthyneura-Pulmonata Basommatophora.

Results of the Austrian-Ceylonese hydrobiological mission 1970 of the 1st Zoological Institute University of Vienna (Austria) and the Department of Zoology of the Vidyalankara University of Ceylon, Kelaniya. Pt 18. Freshwater musssels bivalvia

Till now there have been only two families of Bivalves with four genera known from freshwater in Ceylon. The material used for this study consists of members of three genera. This study deals with the family Unionidae, the family Corbiculidae is only represented by one specimen.

1ST PRINCIPLE CALCULATIONS OF QUASI-PARTICLE ENERGIES FOR BAND STRUCTURES OF SI AND GAAS

We have applied the Green function theory in GW approximation to calculate the quasiparticle energies for semiconductors Si and GaAs. Good agreements of the calculated excitation energies and fundamental energy gaps with the experimental band structures were achieved. We obtained the calculated fundamental gaps of Si and GaAs to be 1.22 and 1.42 eV in comparison to the experimental values of 1.17 and 1.52 eV, respectively. Ab initio pseudopotential method has been used to generate basis wavefunctions and charge densities for calculating dielectric matrix elements and electron self-energies.

1ST PRINCIPLES PSEUDOPOTENTIAL CALCULATIONS OF ZONE BOUNDARY PHONON FREQUENCIES OF III-V-ZINCBLENDE SEMICONDUCTORS

Longitudinal zone boundary X phonon frequencies have been calculated by a first principles pseudopotential method for III-V zincblende semiconductors AlP, AlAs, AlSb, GaP, GaAs, GaSb, InP, InAs and InSb. The phonon frequencies have been evaluated from total energy calculations in the frozen phonon approximation. The calculated phonon frequencies agree very well with the experimental values.

1ST-PRINCIPLES CALCULATIONS FOR QUASI-PARTICLE ENERGIES OF GAP AND GAAS

We have applied the Green-function method in the GW approximation to calculate quasiparticle energies for the semiconductors GaP and GaAs. Good agreement between the calculated excitation energies and the experimental results was achieved. We obtained calculated direct band gaps of GaP and GaAs of 2.93 and 1.42 eV, respectively, in comparison with the experimental values of 2.90 and 1.52 eV, respectively. An ab initio pseudopotential method has been used to generate basis wave functions and charge densities for calculating the dielectric matrix elements and self-enegies. To evaluate the dynamical effects of the screened interaction, the generalized-plasma-pole model has been utilized to extend the dielectric matrix elements from static results to finite frequencies. We presen the calculated quasiparticle energies at various high-symmetry points of the Brillouin zone and compare them with the experimental results and other calculations.

1ST PRINCIPLE CALCULATIONS OF QUASI-PARTICLE ENERGIES FOR BAND STRUCTURES OF SEMICONDUCTORS

We successfully applied the Green function theory in GW approximation to calculate the quasiparticle energies for semiconductors Si and GaAs. Ab initio pseudopotential method was adopted to generate basis wavefunctions and charge densities for calculating dielectric matrix elements and electron self-energies. To evaluate dynamical effects of screened interaction, GPP model was utilized to extend dieletric matrix elements from static results to finite frequencies. We give a full account of the theoretical background and the technical details for the first principle pseudopotential calculations of quasiparticle energies in semiconductors and insulators. Careful analyses are given for the effective and accurate evaluations of dielectric matrix elements and quasiparticle self-energies by using the symmetry properties of basis wavefunctions and eigenenergies. Good agreements between the calculated excitation energies and fundamental energy gaps and the experimental band structures were achieved.

2-DELTA-FUNCTION GENERALIZED PLASMA POLE MODEL FOR 1ST PRINCIPLE CALCULATIONS OF QUASI-PARTICLE ENERGIES IN MANY-ELECTRON SYSTEMS

To evaluate the dynamical effects of the screened interaction in the calculations of quasiparticle energies in many-electron systems a two-delta-function generalized plasma pole model (GPP) is introduced to simulate the dynamical dielectric function. The usual single delta-function GPP model has the drawback of over simplifications and for the crystals without the center of symmetry is inappropriate to describe the finite frequency behavior for dielectric function matrices. The discrete frequency summation method requires too much computation to achieve converged results since ab initio calculations of dielectric function matrices are to be carried out for many different frequencies. The two-delta GPP model is an optimization of the two approaches. We analyze the two-delta GPP model and propose a method to determine from the first principle calculations the amplitudes and effective frequencies of these delta-functions. Analytical solutions are found for the second order equations for the parameter matrices entering the model. This enables realistic applications of the method to the first principle quasiparticle calculations and makes the calculations truly adjustable parameter free.