Hi,all I am always wondering if I defined the quantum numbers of the fermion site basis in the following way, would there be a negative Ndown number (for example, with N=0, Nup=1)?
<QUANTUMNUMBER name="N" min="0" max="2"/> <QUANTUMNUMBER name="Nup" min="0" max="1"/> <QUANTUMNUMBER name="Ndown" min="N-Nup" max="N-Nup"/>
Bo-Nan