I've attached the input file with this mail.

Copied and pasted below:

import pyalps
import numpy as np
import matplotlib.pyplot as plt
import pyalps.plot
import cmath

#prepare the input parameters
parms = []
for D in [80]:
    parms.append( {
        'LATTICE'                               : 'open chain lattice',
        'MODEL'                                 : 'spin',
        'CONSERVED_QUANTUMNUMBERS'              : 'N,Sz',
        'COMPLEX'                               : 1,
        'Jz'                                    : 4.5,
        'Jxy'                                   : 1.0,
#        'E'                                     : 1.0,
        'SWEEPS'                                : 8,
        'NUMBER_EIGENVALUES'                    : 1,
        'L'                                     : 32,
        'MAXSTATES'                             : D,
        'MEASURE_CORRELATIONS[Sx_Sy]'           : 'Sx:Sy',
        'MEASURE_CORRELATIONS[Sy_Sx]'           : 'Sy:Sx',
       } )
#write the input file and run the simulation
input_file = pyalps.writeInputFiles('parm_MP',parms)
res = pyalps.runApplication('dmrg',input_file,writexml=True)

#load all measurements for all states
data = pyalps.loadEigenstateMeasurements(pyalps.getResultFiles(prefix='parm_MP'))

# extract diagonal and offdiagonal correlation data

offdiag_curves1 = []
offdiag_curves2 = []
expectation_of_offdiag_corr1 = []
expectation_of_offdiag_corr2 = []
local_polarization = []

b = open('values.dat','a+')

for run in data:
    for s in run:
        if s.props['observable'] == 'Sx_Sy':  
            od1 = pyalps.DataSet()
            od1.props['observable'] = 'Sx:Sy correlations'
            od1.props['label'] = 'D = '+str(s.props['MAXSTATES'])
            L = int(s.props['L'])
            od1.x = np.arange(L-1)
           
            site1 = np.array([l for l in range(0,L-1)])
            site2 = np.array([l for l in range(1,L)])
            indices_offdiag1 = L*site1 + site2
            od1.y = s.y[0][indices_offdiag1]
           print>>b, '\nSx:Sy correlations with L=32,D=80, E=0\n'
           expectation_of_offdiag_corr1 = od1.y
           offdiag_curves1.append(od1)
            print>>b, expectation_of_offdiag_corr1
            print>>b, indices_offdiag1

        elif s.props['observable'] == 'Sy_Sx':
            od2 = pyalps.DataSet()
            od2.props['observable'] = 'Sy:Sx correlations'
            od2.props['label'] = 'D = '+str(s.props['MAXSTATES'])
            L = int(s.props['L'])
            od2.x = np.arange(L-1)
           
            site1 = np.array([l for l in range(0,L-1)])
            site2 = np.array([l for l in range(1,L)])
            indices_offdiag2 = L*site1 + site2
            od2.y = s.y[0][indices_offdiag2]
            print>>b, '\nSy:Sx correlations with L = 32 & D = 80\n'
            expectation_of_offdiag_corr2 = od2.y
           offdiag_curves2.append(od2)
            print>>b, expectation_of_offdiag_corr2
            print>>b, indices_offdiag2

b.close()


The output I got was:

"dmrg parm_MP.in.xml --write-xml
ALPS DMRG temporary files will be written to .
ALPS/dmrg version 1.0.0 (2006/10/02)
  Density Matrix Renormalization Group algorithm
  for low-dimensional interacting systems.
  available from http://alps.comp-phys.org/
  copyright (c) 2006-2013 by Adrian E. Feiguin
  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 2.1.1
  available from http://alps.comp-phys.org/
  copyright (c) 1994-2012 by the ALPS collaboration.
  Consult the web page for license details.
  For details see the publication:
  B. Bauer et al., J. Stat. Mech. (2011) P05001.

parsing task files ...
ALPS DMRG temporary files will be written to /tmp
ALPS DMRG temporary files will be written to /tmp
Starting task 1.
Cannot evaluate expression Sy(i)

"

rgrds,
Pradeep Thakur



On 30 September 2013 19:09, Matthias Troyer <troyer@phys.ethz.ch> wrote:
It needs to be in the input file

On Sep 30, 2013, at 1:19 PM, German Sinuco <gsinuco@gmail.com> wrote:

Hi there,

Apologize for the naive question, where the parameter COMPLEX should be set? I cannot see it in CMakeCache.txt.

Regards,

German Sinuco




On Sun, Sep 29, 2013 at 2:53 PM, Matthias Troyer <troyer@phys.ethz.ch> wrote:
It will help me explore this issue if you send your input files.

Matthias Troyer

On Sep 28, 2013, at 2:49 PM, pradeep thakur <pskvkthakur@gmail.com> wrote:

Thank you for your time.

With regards,
Pradeep Thakur.


On 28 September 2013 18:11, Matthias Troyer <troyer@phys.ethz.ch> wrote:
We will look into that next week.

Thank you for reporting the problem

Matthias Troyer





On Sep 28, 2013, at 14:33, pradeep thakur <pskvkthakur@gmail.com> wrote:

I had not tried it before. But I tried it just now and still, I get the same msg: "Cannot evaluate expression Sy(i)".


On 28 September 2013 17:58, Matthias Troyer <troyer@phys.ethz.ch> wrote:
Did you set the parameter COMPLEX to 1, so that it actually runs a complex version?

On Sep 28, 2013, at 2:26 PM, pradeep thakur <pskvkthakur@gmail.com> wrote:

Yes, I didn't use sqrt(-1); I simply used I.

I have been using the 4 DMRG codes.

The code which calculates the ground-state energy ran, but yielded results which didn't account for the additional term which had an "I" in it.

In the code for calculating correlations, I tried to calculate Sx:Sy. I defined Sy in the models.xml file as:
<SITEOPERATOR name="Sy" site="x">
  -(I/2)*(Splus(x)-Sminus(x))
</SITEOPERATOR>

The program doesn't run and I get the message: "Cannot evaluate expression Sy(i)".


On 28 September 2013 17:32, Matthias Troyer <troyer@phys.ethz.ch> wrote:
What code are you running?

sqrt(-1) will not work, by the way

On Sep 28, 2013, at 1:56 PM, pradeep thakur <pskvkthakur@gmail.com> wrote:

Dear Sir,

Thanks for your prompt response.

Yes, I did try I. The program for calculating the ground-state energy works as it did, without taking into account the new term (containing I) which I added in the models.xml file. I defined an Sy operator just like Sx. But Sy contains a sqrt(-1). The message I got was "Sy cannot be evaluated".

With regards,
Pradeep Thakur


On 28 September 2013 17:13, Matthias Troyer <troyer@phys.ethz.ch> wrote:
Have you tried I ?

On Sep 28, 2013, at 1:43 PM, pradeep thakur <pskvkthakur@gmail.com> wrote:

> Dear All,
>
> How can I introduce "i" (square-root of -1) into the model library (models.xml file)? I'm unable to define new site- and bond-operators which involve "i".
>
> Any help will be very much appreciated.
>
> With regards,
> Pradeep Thakur
> Dept. of Physics.,
> University of Pune,
> Pune, Maharashtra, INDIA.











--
Dr. German Sinuco
School of Physics and Astronomy
University of Sussex
Brighton - UK
Tel: +44 (0) 1273 678187