TABLE 1 THE STABLE STACKING FAULT ENERGIES ON BASAL AND PRISMATIC PLANE BASAL (mJ/m2) PRISMATIC (mJ/m2) 32.4 255.1 44a [15] 30b [5] 125b [5] aAb initio pseudopotential method bEmpirical pseudopotential method The result on basal plane is in good agreement with other theoretical values 30 mJ/m2 by empirical pseudopotential method of Legrand [5] and 44 mJ/m2 by ab initio pseudopotential method of Chetty and Weinert [15], while Chetty and Weinert calculated only the stable stacking fault energy, and not the GSF energies. However, the stable stacking fault energy on prismatic plane is 255.1 mJ/m2, and it is much different from 125 mJ/m2 by empirical pseudopotential method of Legrand [5]. In order to obtain accurate GSF or stable stacking fault energies, the precision is not sufficient by semi-empirical method, and so ab initio method is effective. SUMMARY The GSF energies on basal and prismatic plane in magnesium has been studied by ab initio pseudopotential method. It is also investigated that the dissociation with the stable stacking fault of a dislocations on prismatic plane is not so clear. We find the lowest energy stable stacking fault point 1/6[112 x] , x=0.76. The calculated GSF energy on basal plane is much lower than that on prismatic plane. This result agrees with that the observed main slip system is basal slip in real magnesium. The stable stacking fault energy, which is the minimum of the GSF energy, is 32.4 mJ/m2 on basal plane and 255.1 mJ/m2 on prismatic plane. In order to obtain accurate GSF or stable stacking fault energies, the precision is not sufficient by semi-empirical method, and so ab initio method is effective. In the future, much knowledge about slip systems will be obtained, if the similar calculations are performed on other slip planes or in other HCP metals. ACKNOWLEDGMENTS We are grateful to the financial support of “the Priority Group of Platform Science and Technology for Advanced Magnesium Alloys, Ministry of Culture, Science and Education” (Grant #11225209) and “The Light Metal Educational Foundation Inc.”. REFERENCES 1. Flynn, P. W., Mote, J. and Dorn, J. E., (1960) Trans. Met. Soc. AIME 218, 416. 2. Stohr, J. F. and Poirer, J., (1972) Phios. Mag. 25, 1313. 3. Vitek, V., (1968) Philos. Mag. 18, 773. 4. Juan, Y., and Kaxiras, E., (1996) Philos. Mag. 74, 1367. 5. Legrand, B., (1974) Philos. Mag. B 49, 171. 6. Hohenberg, P. and Kohn, W., (1964) Phys. Rev. 136, 864. 7. Kohn, W. and Sham, L. J., (1965) Phys. Rev. A 140, 1133. 8. Perdew, J. P. and Wang, Y., (1992) Phys. Rev. B 46, 6671. 9. Troullier, N. and Martins, J. L., (1991) Phys. Rev. B 43, 1993. 10. Kleinman, L. and Bylander, D. M., (1982) Phys. Rev. Lett. 48, 1425. 11. Louie, S. G., Froyen, S. and Cohen, M. L., (1982) Phys. Rev. B 26, 1738. 12. Teter, M. P., Payne, M. C. and Allan, D. C., (1989) Phys. Rev. B 40, 12225.
RkJQdWJsaXNoZXIy MjM0NDE=