Coherent anomaly method for classical Heisenberg model

✍ Scribed by Krishna G. Chakraborty

• Book ID: 103896177
• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 504 KB
• Volume: 227
• Category: Article
• ISSN: 0378-4371
• DOI: 10.1016/0378-4371(95)00415-7

✦ Synopsis

The power series coherent anomaly method is applied to study the critical properties of a classical Heisenberg model. The values of true critical temperature T* are obtained. Using these results the estimation of critical exponent y for the zero-field static susceptibility has been made. The results for T* are in good agreement with those obtained from the ratio method and the Pad6 approximant analysis of the direct susceptibility series. But the results for y are found to be different. It is seen that ? for bcc and fcc lattices is approximately equal to 4/3, while for the sc lattice y >> 4/3, in disagreement with the mean experimental value of 4/3. With the proposal of a possible correction due to confluent singularities for sc model we obtain the following expression for susceptibility: X = a(1 -tc)-4/3[1 + B(1 --to) 3.] , with tc = xc/x*, xc = J/kB Tc, k~ being the Boltzmann constant, J the nearest-neighbour exchange constant, T~ the critical temperature. B and a are numerical constants. A*, the confluent correction has been found to be 0.42 for the sc lattice and non-existent in bcc and fcc lattices.