Just use I for i On Oct 28, 2012, at 2:16 PM, "Forwordom" <mljphy@qq.com> wrote:

Hi alps users and developers I want to simulate a lattice phase transition in external magnetic along x,y,z direction by using dmrg.I have to couple site operator with external magnetic field. But how to edit a complex number in the ALPS models.xml to get site operator Sy=1/2i(Splus-Sminus). Thanks in advance for your reply.