Hi, users and developers
As you can see, I am working on Kondo lattice with ALPS. I find something strange: I calculate the situation: A L=2 Kondo lattice with 2 spin and 1 fermion, t=10,J=2, the ALPS sparsediag shows the ground energy is around -20. And it is obvious that such a simple situation can be solved exactly with bare hand, but the result I find out with my pencil is only -11, also with the different number of energy levels from ALPS. I am quite confident in the -11 result supported by the SU(2) and parity symmetry, besides other results of my pencil calculation (not shown here) are consistent with the published papers,too. Can you guys tell me why this happens ? An error of ALPS or I use it in a wrong way?
ps: Even I turn the TRANSLATION_SYMMETRY=false, the spin correlation results are all zero with is not only contradict with my pencil result, but also with the ALPS DMRG result. How can I fix it???
Any advice is welcome!!!!!
Here is the input file: ------------------------PARAMETER FILE-----------------------------------
LATTICE_LIBRARY="my_lattices.xml" LATTICE="periodic chain lattice" MODEL_LIBRARY="my_models.xml" MODEL="Kondo lattice" CONSERVED_QUANTUMNUMBERS="N" N_total=3 TRANSLATION_SYMMETRY=false TOTAL_MOMENTUM=0 MEASURE_CORRELATIONS[Diagonal spin correlations]=Sz MEASURE_CORRELATIONS[Offdiagonal spin correlations]="Splus:Sminus" L=2 mu=0 t=10 {J=2}
--------------------LATTICE-----------------------------------------------------
<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>
<UNITCELL name="heavy fermion" dimension="1"> <VERTEX type="0"/> <VERTEX type="1"/> <EDGE type="0"><SOURCE vertex="1" offset="0"/><TARGET vertex="1" offset="1"/></EDGE> <EDGE type="1"><SOURCE vertex="1" offset="0"/><TARGET vertex="2" offset="0"/></EDGE> </UNITCELL>
<LATTICEGRAPH name="periodic chain lattice"> <FINITELATTICE> <LATTICE ref="chain lattice"/> <PARAMETER name="L" default="4"/> <EXTENT size="L"/> <BOUNDARY type="periodic"/> </FINITELATTICE> <UNITCELL ref="heavy fermion"/> </LATTICEGRAPH>
</LATTICES>
--------------------------------------MODELS-------------------------------------------
<MODELS> <SITEBASIS name="spin"> <QUANTUMNUMBER name="N" min="1" max="1" type="fermionic"/> <QUANTUMNUMBER name="S" min="1/2" max="1/2" type="fermionic"/> <QUANTUMNUMBER name="Sz" min="-S" max="S"/> <OPERATOR name="Splus" matrixelement="1"> <CHANGE quantumnumber="Sz" change="1"/> </OPERATOR> <OPERATOR name="Sminus" matrixelement="1"> <CHANGE quantumnumber="Sz" change="-1"/> </OPERATOR> <OPERATOR name="Sz" matrixelement="Sz"/> <OPERATOR name="n" matrixelement="N"/> </SITEBASIS>
<SITEBASIS name="fermion"> <QUANTUMNUMBER name="Nup" min="0" max="1" type="fermionic"/> <QUANTUMNUMBER name="Ndown" min="0" max="1" type="fermionic"/> <QUANTUMNUMBER name="N" min="Nup+Ndown" max="Nup+Ndown"/> <QUANTUMNUMBER name="Sz" min="(Nup-Ndown)/2" max = "(Nup-Ndown)/2"/> <OPERATOR name="Splus" matrixelement="1"> <CHANGE quantumnumber="Nup" change="1"/> <CHANGE quantumnumber="Ndown" change="-1"/> <CHANGE quantumnumber="Sz" change="1"/> </OPERATOR> <OPERATOR name="Sminus" matrixelement="1"> <CHANGE quantumnumber="Nup" change="-1"/> <CHANGE quantumnumber="Ndown" change="+1"/> <CHANGE quantumnumber="Sz" change="-1"/> </OPERATOR> <OPERATOR name="Sz" matrixelement="(Nup-Ndown)/2"/> <OPERATOR name="c_down" matrixelement="1"> <CHANGE quantumnumber="Ndown" change="-1"/> <CHANGE quantumnumber="N" change="-1"/> <CHANGE quantumnumber="Sz" change="1/2"/> </OPERATOR> <OPERATOR name="cdag_down" matrixelement="1"> <CHANGE quantumnumber="Ndown" change="1"/> <CHANGE quantumnumber="N" change="1"/> <CHANGE quantumnumber="Sz" change="-1/2"/> </OPERATOR> <OPERATOR name="c_up" matrixelement="1"> <CHANGE quantumnumber="Nup" change="-1"/> <CHANGE quantumnumber="N" change="-1"/> <CHANGE quantumnumber="Sz" change="-1/2"/> </OPERATOR> <OPERATOR name="cdag_up" matrixelement="1"> <CHANGE quantumnumber="Nup" change="1"/> <CHANGE quantumnumber="N" change="1"/> <CHANGE quantumnumber="Sz" change="+1/2"/> </OPERATOR> <OPERATOR name="n" matrixelement="Nup+Ndown"/> <OPERATOR name="n_up" matrixelement="Nup"/> <OPERATOR name="n_down" matrixelement="Ndown"/> </SITEBASIS>
<BASIS name="Kondo lattice"> <SITEBASIS type="0" ref="fermion"/> <SITEBASIS type="1" ref="spin"/> <CONSTRAINT quantumnumber="N" value="N_total"/> <!--<CONSTRAINT quantumnumber="Sz" value="Sz_total"/>--> </BASIS>
<BONDOPERATOR name="exchange" source="x" target="y"> Sz(x)*Sz(y)+1/2*(Splus(x)*Sminus(y)+Sminus(x)*Splus(y)) </BONDOPERATOR>
<BONDOPERATOR name="fermion_hop" source="x" target="y">
cdag_up(x)*c_up(y)+cdag_up(y)*c_up(x)+cdag_down(x)*c_down(y)+cdag_down(y)*c_down(x)
</BONDOPERATOR>
<HAMILTONIAN name="Kondo lattice"> <PARAMETER name="mu" default="0"/> <PARAMETER name="t" default="1"/> <PARAMETER name="J" default="1"/> <BASIS ref="Kondo lattice"/> <SITETERM type="0" site="i"> -mu*n(i) </SITETERM> <SITETERM type="1"> 0 </SITETERM> <BONDTERM type="0" source="i" target="j"> -t*fermion_hop(i,j) </BONDTERM> <BONDTERM type="1" source="i" target="j"> J*exchange(i,j) </BONDTERM> </HAMILTONIAN>
</MODELS>
-------------------------------------END---------------------------------
Bo-Nan