Dear All,

My question is related to the calculated results of the below code. This entails MPS implantation to reach energy gap of a Heisenberg chain in the presence of a magnetic field. We wrote:

%%%%%%%%%%%%%%% Start %%%%%%%%%%%%%%%%%%%%%%% import pyalps import numpy as np import matplotlib.pyplot as plt import pyalps.plot parms = [] for hz in [0.0, 0.2, 0.4, 0.6, 0.8, 1.0]: parms.append( { 'LATTICE' : "open chain lattice", 'MODEL' : "spin", 'CONSERVED_QUANTUMNUMBERS' : 'N,Sz', 'Sz_total' : 0, 'J' : 1, 'h' : hz, 'SWEEPS' : 4, 'L' : 32, 'MAXSTATES' : 100, 'NUMBER_EIGENVALUES' : 2 } )

input_file = pyalps.writeInputFiles('parm_spin_one_half_gap',parms) res = pyalps.runApplication('mps_optim',input_file,writexml=True)

data = pyalps.loadEigenstateMeasurements(pyalps.getResultFiles(prefix='parm_spin_one_half_gap')) energies = np.empty(0) for s in data[0]: if s.props['observable'] == 'Energy': energies = s.y else: print(s.props['observable'], ':', s.y[0]) energies.sort() print('Energies:', end=' ') for e in energies: print(e, end=' ') print('\nGap:', abs(energies[1]-energies[0]))

%%%%%%%%%%%%%%% END %%%%%%%%%%%%%%%%%%%%%%%

Although, in the file "parm_spin_one_half_gap.in.xml" there are expensive information such as energies for any "hz", we need to collect all results in a *.dat or *.txt file. For instance, a "file.txt" as: hz gap 0.0 0.11 0.2 0.12 0.4 0.14 0.6 0.15

How can we generate such a file?!