Hi Ryo
For spin-1/2 systems, I tried lattices from L=4,6,...22 and got a gap of 0.025 after extrapolation (between Sz=0 and Sz=1); can I consider this good enough to call it gapless, or do I need bigger lattices?
For spin-2, I tried lattices from L=4,6,8,10, and got a gap of 0.089; I guess the non-linear sigma model predicts S=2 system to have a gap of 0.071. Beyond L=12, it takes really long; what system size is considered "reasonable" for evalauting gap of spin-2?
Thanks, Vipin
On Sat, 19 Jun 2010, Ryo IGARASHI wrote:
Hi, Vipin,
On Fri, Jun 18, 2010 at 7:22 PM, Vipin Varma varma@th.physik.uni-bonn.de wrote:
Thanks for the reply; so I guess I should consider chains with odd number of sites (whether for spin-1/2 or spin-1 chains) to calculate the corresponding topological excitations. Is this correct?
No. You should think Sz_total=1 subspace as 2-spinon excited states. 2-spinon excited states are what experimentally observed (from e.g. neutron).
Best regards,
Ryo IGARASHI, Ph.D. rigarash@hosi.phys.s.u-tokyo.ac.jp OpenPGP fingerprint: BAD9 71E3 28F3 8952 5640 6A53 EC79 A280 6A19 2319