Hi,

To use “x” in the model and/or parameters, you need to use an inhomogeneous lattice.
Anyway, since your model seems to work with the dmrg application, I think the problem is somewhere else.

Which version of ALPS do you have installed?
We fixed a few issues with the inhomogeneous lattices a few months ago, and there was no recent official release.
I would suggest you to use the latest /trunk version of ALPS.
(previous mails in the mailing list should be pretty explanatory on how to get the latest trunk version)

Best regards,
Michele

--
ETH Zurich
Michele Dolfi
Institute for Theoretical Physics
HIT G 32.4
Wolfgang-Pauli-Str. 27
8093 Zurich
Switzerland

dolfim@phys.ethz.ch
www.itp.phys.ethz.ch

+41 44 633 78 56 phone
+41 44 633 11 15 fax 

On 24 May 2016, at 08:04, 北尘心 <740572900@qq.com> wrote:

Previously, I used DMRG to calculate the model containing the external potential, but now I would like to try to use MPS to calculate it.When i use MPS, I meet a question of  potential.


My potential setting  like this

<SITETERM site="i">

<PARAMETER name="mu#" default="mu"/>

<PARAMETER name="U#" default="U"/>

<PARAMETER name="Vout" default="0"/>

-mu#*n(i)+U#*n_up(i)*n_down(i)+Vout*((x-(L-1)/2.0)^2)*n(i)

</SITETERM>


I use the model ,lattice and command like I used in DMRG, but the computer prompt like :

Exception thrown:

Cannot evaluate x


By using DMRG, it can be calculated correctly, but MPS will prompt the error, i wonder what should I do to correct it?


It is highly grateful for your any suggestion.


Yours sincerely,


Xingbo Wei

Zhejiang Normal University

Jinhua,230014,

China



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