Dear ALPS community,

I am using the DMRG programs (with OBC) to calculate the spin-spin correlations of a spin chain.

Suppose N is the number of sites in the chain. My question is - while using the DMRG programs, is it possible to restrict calculations of correlations to a distance "d" between two sites where d<<N?

Eg. instead of calculating all the N**2 correlations between all the spins, calculate only nearest neighbours or N-1 correlations?

I want to obtain correlations for N>128 sites. ~60GB of RAM on a workstation is proving insufficient for this. I have been able to obtain local spin components <S_i^a> (a=x,y,z) for N=512 too. But, for the correlation calculations, N**2 correlations require more than 4 times the available RAM even for N=128. So I have to use smaller N, which leads to pronounced effects due to finite size and boundaries. Hence, the question.

Thanks very much.

with regards, Pradeep Thakur.