ALPS community,
I am interested in calculating the states and the spin-spin correlation functions for a dimerized chain. This type of structure is sometimes called an alternating chain. It consists of spins coupled along one-dimension with alternating strong and weak Heisenberg exchange parameters: J0---J1---J0---J1---J0---
Using the tutorials and the ALPS website, I have assembled what I think are the correct UNITCELL and LATTICEGRAPH (see end of message).
Q1: Is there a way to check this definition visually? The wiki suggests the command printgraph parameter_file
Q2: does the predefined 'MODEL' "spin" account for J0 and J1 exchange?
Q3: Can 'S' also be a conserved quantum number.
Thanks for your assistance.
Matt Stone
parms = [{ 'LATTICE' : "dimechain", 'LATTICE_LIBRARY' : "latticeCN.xml", 'MODEL' : "spin", 'local_S' : 0.5, 'J0' : 1, 'J1' : 0.125, 'L' : 6, 'CONSERVED_QUANTUMNUMBERS' : 'Sz', 'MEASURE_CORRELATIONS[Diagonal spin correlations]=' : 'Sz', 'MEASURE_CORRELATIONS[Offdiagonal_spin_correlations1]' : 'Splus:Sminus', 'MEASURE_CORRELATIONS[Offdiagonal_spin_correlations2]' : 'Sminus:Splus, 'D' : 0.0, 'h' : 0.0, }]
<UNITCELL name="anisotropic1d" dimension="1"> <VERTEX/> <EDGE type="0"> <SOURCE vertex="1" offset="0"/> <TARGET vertex="1" offset="0.5"/> </EDGE> <EDGE type="1"> <SOURCE vertex="1" offset="0.5"/> <TARGET vertex="1" offset="1"/> </EDGE> </UNITCELL>
<LATTICEGRAPH name = "dimechain" vt_name="dimechainLattice"> <FINITELATTICE> <LATTICE ref="chain lattice"/> <EXTENT dimension="1" size="L"/> <BOUNDARY dimension="1" type="periodic"/> </FINITELATTICE> <UNITCELL ref="anisotropic1d"/> </LATTICEGRAPH>
<!-- From the default lattices --> <LATTICE name="chain lattice" dimension="1"> <PARAMETER name="a" default="1"/> <BASIS><VECTOR>a</VECTOR></BASIS> <RECIPROCALBASIS><VECTOR>2*pi/a</VECTOR></RECIPROCALBASIS> </LATTICE>