Hi, Matthias and ALPS people

I recheck the spin operator for fermion on wiki (where the matrix elements of Splus and Sminus are both given )http://en.wikipedia.org/wiki/Anti-symmetric_operator, but it seems the matrix elements of Splus and Sminus in SITEBASIS "fermion" and "alternative fermion" shall be one. I do not mean to be offensive. Trust me, this problem has already driven myself crazy. Maybe it is my mistake, so can you ALPS people be so kind to tell me where I am wrong or your special consideration when you define the above two matrix elements?

Bo-Nan

2013/3/5 Bo-Nan JIANG <bonanjiang@gmail.com>

Hi,all
we all know, for the angular momentum, the operator matrix element of Jplus is sqrt(J*(J+1)-Jz(Jz+1)) and for Jminus, it is sqrt(J*(J+1)-Jz(Jz-1)). Just as ALPS defines in SITEBASIS "spin". So, it is straightforward that the spin-1/2 fermion with S=1/2, the matrix elements of Splus and Sminus shall be sqrt((1/2)*(1/2+1)-(-1/2)(-1/2+1))=1 and sqrt((1/2)*(1/2+1)-1/2(1/2-1))=1 respectively. If I am right, then why you guys define the matrix element of Splus and Sminus in SITEBASIS "fermion" and "alternative fermion" all equal to 1/2?

Bo-Nan

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Stay foolish,Stay hungry.