On Feb 6, 2016, at 12:00 PM, comp-phys-alps-users-request@lists.phys.ethz.ch wrote:

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Today's Topics:

1. Topological properties and exact diagonalization (Marco Di Liberto)

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Message: 1 Date: Fri, 5 Feb 2016 18:53:10 +0100 From: Marco Di Liberto m.f.diliberto@uu.nl To: "comp-phys-alps-users@lists.phys.ethz.ch" comp-phys-alps-users@lists.phys.ethz.ch Subject: [ALPS-users] Topological properties and exact diagonalization Message-ID: CAN_y_feEzPAB-EoNTYQrmnF__O+O+gWgZW9HSgF0-XGvgttDnQ@mail.gmail.com Content-Type: text/plain; charset="utf-8"

Hi,

I am wondering whether it is easily possible to extract topological quantities, like the chern number, for a many-body system using the exact diagonalization routines of alps.

To compute the Chern number in ED you can apply twisted boundary condition to a torus; compute wave function overlaps on a mesh; then sum them up.

However, this is is not easily done with ALPS-ED. Another option to extract topological quantities is to insert flux to a cylindrical system and observe charge pumping from physical observables such as occupation number.

Moreover, can one get the wavefunction components from the exact diagonalization routines?

By setting “PRINT_EIGENVECTORS” to true, one can print out the basis and wavefunctions.

Regards,

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Marco Di Liberto