quickISObasis

◼ quickISObasis[ops] generates an (I,S) basis, i.e. a basis with well defined total isospin I and total spin S quantum numbers.

◼ Operators ops must be given in the stripped form without creation and spin index.

◼ Isospin phase may be defined using nnop. See also isospin.

◼ See also: qsbasis, qszbasis, transformtoIS, isospin.

Further examples

Load sneg and declare some quantities

<< sneg`sneg`;
snegfermionoperators[c];

ClearAll[nnop];
quickISObasis[{c[1]}] // MatrixForm
quickISObasis[{c[1], c[2]}] // MatrixForm
quickISObasis[{c[1], c[2], c[3]}] // MatrixForm

Note the subtle difference in the sign of the first basis state in the (0,0) subspace.

nnop[c[1]] = 1;
nnop[c[2]] = 1;
quickISObasis[{c[1], c[2]}] // MatrixForm

    
nnop[c[1]] = 1;
nnop[c[2]] = 0;
quickISObasis[{c[1], c[2]}] // MatrixForm