Solution of Bose Hubbard model using ARPACK

[Sayan Lahiri]

Sir currently I am trying to solve a system which has 8 sites and each site can have 3 possible states(0 or 1 or 2).So the dimension of matrix is 6561*6561.The lapack works good till 3000*3000.But for larger system it fails.I have studied the dsdrv1.f example from arpack where they have solved the problem for central difference discretization of the 2-dimensional Laplacian on the unit square [0,1]x[0,1] with zero Dirichlet boundary condition.But I can not understand what changes i should make in my case.Please help

 

[Sayan Lahiri]

I can not understand how to apply the example given in arpack

 

[DrClaude]

Can you give more details of what you are trying to do and what you have tried?