XDiag

A Julia library to perform efficient Exact Diagonalizations of quantum many body systems.

• Basic algebra of operators in quantum many-body systems
• Iterative linear algebra for computing eigendecompositions and time-evolutions (e.g. Lanczos algorithm)
• Local spin, t-J, or fermionic models
• Full support of generic space group symmetries
• parallelization using OpenMP
• based on C++ library xdiag

Enter the package mode using ] in the Julia REPL and add type

add XDiag

That's it!

using XDiag

let 
    N = 16;
    nup = N ÷ 2;
    block = Spinhalf(N, nup);
    
    # Define the nearest-neighbor Heisenberg model
    ops = OpSum()
    for i in 1:N
        ops += Op("HB", "J", [i, mod1(i+1, N)])
    end
    ops["J"] = 1.0;

    set_verbosity(2);           # set verbosity for monitoring progress
    e0 = eigval0(ops, block);   # compute ground state energy

    println("Ground state energy: $e0");
end

The full documentation is available at awietek.github.io/xdiag.

author: Alexander Wietek license: Apache License 2.0