Application of Dyson-type boson mapping method to intermediately-excited collective states

点击翻译按钮获取中文摘要

(1) We have completed a set of computer programs to analyze multi-octupole-phonon coolective states in medium-heavy nuclei. (The source programs consist of about 40,000 lines.)(2) These programs have been applied for the multi-octupole-phonon excited states in ^<146,148>Gd. The precise numerical results show that the coupling effect between neutron pair and octupole particlehole modes plays and essential role for the enhancement of octupole collectivity. The result has been published in our paper, "K.Takada and Y.R.Shimizu : Two-Octupole-Phonon States in ^<146,148>Gd, Prog.Theor.Phys.95, No.6 (1996) 1121-1143".(3) In developing the programs mentioned above, we have invented a "simplified hashing method" published in a paper "K.Takada : To apply hashing method to numerical calculations, Report of Computer Center, Kyushu University, 28 (1995) 129". We found that our new hashing method is quite useful for a big size of numerical calculation which needs a huge amount of core memories. Using this method, we have made it possible to carry out a big size of computation, which appeared impossible even on a main frame before, on a small personal computer.(4) Since the above programs are in the particle-hole representation, the particle-number conservation is strictly fulfillled. However they are applicable only for a restricted area adjacent to closed shell. To overcome the defect, we have developed a new algolithm of program for the Dyson boson mapping in the quasi-particle representation, the main part of which has been completed. The application of this new program for a wide range of realistic nuclei is a problem of near future.