Hi Michael,

Brilliant, that's just what I needed! Thank you very much.

Joseph On 30 Jul 2013, at 11:00, comp-phys-alps-users-request@lists.phys.ethz.ch wrote:

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Today's Topics:

1. Possible Measurements in TEBD code (Joseph Prentice)
2. Re: Possible Measurements in TEBD code (Michael Wall)

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Message: 1 Date: Mon, 29 Jul 2013 10:02:01 +0000 From: Joseph Prentice Joseph.Prentice@physics.ox.ac.uk To: "comp-phys-alps-users@lists.phys.ethz.ch" comp-phys-alps-users@lists.phys.ethz.ch Subject: [ALPS-users] Possible Measurements in TEBD code Message-ID: 747861816F6A5C47BE50FCA07F5B2B4A0DD609@EXCHNG16.physics.ox.ac.uk Content-Type: text/plain; charset="us-ascii"

Hi all,

I'm attempting to look at spin correlation functions, both nearest neighbour and next nearest neighbour, near the centre of an XXZ chain that is undergoing a quench using the TEBD code. As far as I can tell from the documentation, these measurements are hardcoded in to the TEBD code, but the documentation gives no clue on how to access them. In effect, what I would like to know is what can I write into the following line of Python (taken from the second TEBD tutorial): Data = pyalps.load.loadTimeEvolution(pyalps.getResultFiles(prefix='tutorial_2a'), measurements=['Local Magnetization']) instead of 'Local Magnetization', in order to obtain the correlation functions, and also how I could then define which sites the correlation function will be calculated using. I think a question similar to this was asked in January, but there was no answer.

Thank you very much in advance! Joseph Prentice

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Message: 2 Date: Mon, 29 Jul 2013 20:23:15 -0600 From: Michael Wall mwall.physics@gmail.com To: comp-phys-alps-users@lists.phys.ethz.ch, Lincoln Carr lcarr@mines.edu, "ebekarog@mines.edu" ebekarog@mines.edu Subject: Re: [ALPS-users] Possible Measurements in TEBD code Message-ID: CA+DwVMoxud1UCTkCHgGLXYfDDW8V0mZR_ky=B2jA7zR2Ny6S1A@mail.gmail.com Content-Type: text/plain; charset="iso-8859-1"

Hi Joseph,

Indeed, the measurements are hardcoded in the present version of the code. You can determine the syntax of the outputs by looking at one of the output *.h5 files. There's too many to list here, so I've attached a screenshot. For the correlation functions which are computed, they are computed for all pairs of sites i and j and returned as a matrix. Hope this helps.

-Michael [image: Inline image 1]

Hi all,

...

I'm attempting to look at spin correlation functions, both nearest neighbour and next nearest neighbour, near the centre of an XXZ chain that is undergoing a quench using the TEBD code. As far as I can tell from the documentation, these measurements are hardcoded in to the TEBD code, but the documentation gives no clue on how to access them. In effect, what I would like to know is what can I write into the following line of Python (taken from the second TEBD tutorial): Data = pyalps.load.loadTimeEvolution(pyalps.getResultFiles(prefix='tutorial_2a'), measurements=['Local Magnetization']) instead of 'Local Magnetization', in order to obtain the correlation functions, and also how I could then define which sites the correlation function will be calculated using. I think a question similar to this was asked in January, but there was no answer. Thank you very much in advance! Joseph Prentice