QuantumATK Forum
QuantumATK => General Questions and Answers => Topic started by: zhangguangping on December 22, 2010, 06:09
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I have encountered a convergence problem,for my system,for other bias there is no problem in convergence.Even I have got the convergence for V=1.0, 1.5 ,2.0V, but for V=1.2Vand 1.4V,the convergence is hard to achived,I calculate V=1.4V using a initio guess from V=1.5.Even if I choose diagonal_mixing_parameter = 0.00001,my tolerance=0.0001.
The convergence process is as the following,the q varies slightly, but the Ebs and dRho....
Who can tell me the underling reason?
in addition there is nothing strange for the spectrum at V=1.0V and 1.5V.
Thanks in advance.
......
# sc 204 : q = 585.99929 e Ebs = -536.20515 Ry dRho = 1.1830E-03
# sc 205 : q = 585.99917 e Ebs = -536.76316 Ry dRho = 8.6365E-04
# sc 206 : q = 585.99915 e Ebs = -536.81562 Ry dRho = 1.0491E-03
# sc 207 : q = 585.99923 e Ebs = -536.82648 Ry dRho = 1.0925E-03
# sc 208 : q = 585.99924 e Ebs = -536.77731 Ry dRho = 9.0449E-04
# sc 209 : q = 585.99924 e Ebs = -536.78277 Ry dRho = 9.4113E-04
# sc 210 : q = 585.99971 e Ebs = -536.76664 Ry dRho = 8.7112E-04
# sc 211 : q = 585.99926 e Ebs = -536.20515 Ry dRho = 1.1830E-03
# sc 212 : q = 585.99914 e Ebs = -536.77953 Ry dRho = 9.2239E-04
# sc 213 : q = 585.99914 e Ebs = -536.82901 Ry dRho = 1.0987E-03
# sc 214 : q = 585.99923 e Ebs = -536.82727 Ry dRho = 1.0910E-03
# sc 215 : q = 585.99926 e Ebs = -536.77637 Ry dRho = 8.9766E-04
# sc 216 : q = 585.99926 e Ebs = -536.77149 Ry dRho = 8.9816E-04
# sc 217 : q = 585.99971 e Ebs = -536.76023 Ry dRho = 8.4768E-04
# sc 218 : q = 585.99926 e Ebs = -536.20514 Ry dRho = 1.1829E-03
# sc 219 : q = 585.99921 e Ebs = -536.77788 Ry dRho = 9.1608E-04
# sc 220 : q = 585.99944 e Ebs = -536.78886 Ry dRho = 9.4414E-04
# sc 221 : q = 585.99913 e Ebs = -536.34500 Ry dRho = 6.5681E-04
# sc 222 : q = 585.99912 e Ebs = -536.83700 Ry dRho = 1.1288E-03
# sc 223 : q = 585.99913 e Ebs = -536.83785 Ry dRho = 1.1306E-03
# sc 224 : q = 585.99925 e Ebs = -536.83654 Ry dRho = 1.1317E-03
# sc 225 : q = 585.99919 e Ebs = -536.76811 Ry dRho = 8.6867E-04
# sc 226 : q = 585.99919 e Ebs = -536.80860 Ry dRho = 1.0286E-03
# sc 227 : q = 585.99971 e Ebs = -536.80245 Ry dRho = 9.9508E-04
# sc 228 : q = 585.99914 e Ebs = -536.20515 Ry dRho = 1.1829E-03
# sc 229 : q = 585.99916 e Ebs = -536.82852 Ry dRho = 1.0964E-03
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try different mixing schemes or tune the history steps used in the mixing procedure.
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You can also try to improve the sampling of energies on the real axis contour, this will decrease the error
I would recommend that you upgrade to the latest version of ATK 2010.8.2 which has a new double contour technique which stabilize finite bias calculations and thus is easier to converge.
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try different mixing schemes or tune the history steps used in the mixing procedure.
Thanks ,when i use 0.1 as the mixing,one of the task coverged very fast (in five steps).Thanks for your suggestion.
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You can also try to improve the sampling of energies on the real axis contour, this will decrease the error
I would recommend that you upgrade to the latest version of ATK 2010.8.2 which has a new double contour technique which stabilize finite bias calculations and thus is easier to converge.
Thank you all the same.
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try different mixing schemes or tune the history steps used in the mixing procedure.
Thanks ,when i use 0.1 as the mixing,one of the task coverged very fast (in five steps).Thanks for your suggestion.
what do you mean when you say that you have used 0.1 as the mixing, i can't seem to find such an option in atk calculator settings.
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IterationControlParameters(damping_factor=0.1)