Thanks to all who answered. Synge - your practical advice most appreciated. I do not know whether it applies to all MC-codes. I run QMC (worm) on different twists of Bose-Hubbard.

Mathias. Thanks. That I found after asking. BUT still- ...

you wrote

Date: Wed, 28 Jan 2009 09:31:00 -0800 From: Matthias Troyer troyer@phys.ethz.ch

If your parameters are called parms, then parameter2xml creates a file

parms.in.xml, and the simulation creates a file parms.out.xml . The latter is the file to edit.

I did exactly as you suggest - My parameter file is called prl I changed status from "finished" to "running" in prl.out.xml. I increased SWEEPS in prl.task1.out.xml. Then I execute

worm --Tmin 50 parms.out.xml and get info: - I copy the screen here

kuba@b52:~/Pr3 $ worm --Tmin 50 prl.out.xml Worm algorithm quantum Monte Carlo simulation v2.0 copyright (c) 1997-2007 by Simon Trebst trebst@comp-phys.org and Matthias Troyer troyer@comp-phys.org for details see the publication: A.F. Albuquerque et al., J. of Magn. and Magn. Materials 310, 1187 (2007).

using the ALPS parallelizing scheduler copyright (c) 1994-2006 by Matthias Troyer troyer@comp-phys.org. see Lecture Notes in Computer Science, Vol. 1505, p. 191 (1998).

based on the ALPS libraries version 1.3.3 available from http://alps.comp-phys.org/ copyright (c) 1994-2008 by the ALPS collaboration. Consult the web page for license details. For details see the publication: A.F. Albuquerque et al., J. of Magn. and Magn. Materials 310, 1187 (2007).

parsing task files ... Loading information about run 1 from file /users/champ/kuba/Pr3/prl.task1.out.run1 Cannot change parameter SWEEPS Cannot open simulation file /users/champ/kuba/Pr3/prl.task1.out.xml. Task 1 does not exist. Finished with everything.

Please note the info Cannot change parameter SWEEPS.

So what I am doing wrongly?

regards Kuba (Jakub Zakrzewski)