摘要The computations of the phonon dispersion curves (PDC) of four equiatomic Li-based binary alloys, namely Li0.5Na0.5, Li0.5K0.5, Li0.5Rb0.5 and Li0.5Cs0.5, to second order in the local model potential is discussed in terms of the real-space sum of Born von Karman central force constants. Instead of the concentration average of the force constants of metallic Li, Na, K, Rb and Cs, the pseudo-alloy atom (PAA) is adopted to compute directly the force constants of four equiatomic Li-based binary alloys. The exchange and correlation functions due to Hartree (H) and Ichimaru--Utsumi (IU) are used to investigate the influence of screening effects. The phonon frequencies of four equiatomic Li-based binary alloys in the longitudinal branch are more sensitive to the exchange and correlation effects in comparison with the transverse branches. However, the frequencies in the longitudinal branch are suppressed due to IU-screening function than the frequencies due to static H-screening function.
Abstract：The computations of the phonon dispersion curves (PDC) of four equiatomic Li-based binary alloys, namely Li0.5Na0.5, Li0.5K0.5, Li0.5Rb0.5 and Li0.5Cs0.5, to second order in the local model potential is discussed in terms of the real-space sum of Born von Karman central force constants. Instead of the concentration average of the force constants of metallic Li, Na, K, Rb and Cs, the pseudo-alloy atom (PAA) is adopted to compute directly the force constants of four equiatomic Li-based binary alloys. The exchange and correlation functions due to Hartree (H) and Ichimaru--Utsumi (IU) are used to investigate the influence of screening effects. The phonon frequencies of four equiatomic Li-based binary alloys in the longitudinal branch are more sensitive to the exchange and correlation effects in comparison with the transverse branches. However, the frequencies in the longitudinal branch are suppressed due to IU-screening function than the frequencies due to static H-screening function.
[1] Gajjar P N, Vora A M, Patel M H and Jani A R 2000 Different Disordered Systems ed Furukawa et al (Allahabad: INDIASPublisher) p 57 [2] Vora Aditya M 2007 J. Phys. Chem. Sol. 68 6725 [3] Gajjar P N, Patel M H, Thakore B Y and Jani A R 2002 Commun. Phys. 12 81 [4] Gajjar P N, Thakore B Y, Patel H K and Jani A R 1995 Acta Phys. Pol. A 88 489 [5] Gajjar P N, Thakore B Y, Luhar J S and Jani A R 1995 Physica B 215 293 [6] Wallis R F, Maradudin A A, Eguiluz A G, Quong A A,Franchini A and Santara G 1993 Phys. Rev. B 48 6043 [7] Soma T, Ohsugi H and Matsuo Kagaya H 1984 Phys.Status Solidi B 124 525 [8] Kamitakahara W A and Copley J R D 1978 Phys. Rev. B 18 3772 [9] Chushak Y A and Baumketner A. 1999 Eur. Phys. J. B 7 129 [10] Aschroft N W 1966 Phys. Lett. 23 48 [11] Vora Aditya M 2006 Chin. Phys. Lett. 23 1872 [12] Mu Y M and Tao R B 1991 Chin. Phys. Lett. 8195 [13] Zhong H W and Tang Y 2006 Chin. Phys. Lett. 23 1965 [14] Vora Aditya M 2006 Physica C 450 135 Vora Aditya M 2007 Compu. Mater. Sci. 40 492 [15] Ichimaru S and Utsumi K 1981 Phys. Rev. B 247385 [16] Harrison W 1999 Elementary Electronic Structure(Singapore: World Scientific) [17] Cohen M L and Heine V 1970 Solid State Physics edEhrenreich H et al (New York: Academic) vol 24 p 196 [18] Shimada K 1974 Phys. Status Solidi B 61 325 [19] Smith H G, Doling G, Nacklaw R M, Vijayraghvan P R andWikinson M K 1968 Neutron Inelastic Scattering 1 149 [20] Woods A D B, Brockhouse B N, Marck R H, Stewart A T andBowerson R 1962 Phys. Rev. B 128 1112 [21] Cowley R A, Woods A D B and Doling G 1966 Phys.Rev. B 150 487 [22] Copley J R D and Brockhouse B N 1973 Can. J. Phys. 51 657
2008, Vol. 25 
