PauliChainExpand[exp]
expands all Pauli chains with explicit indices using linearity, e.g. PCHN[CSIS[p1]+CSIS[p2]+m,i,j]
becomes PCHN[CSIS[p1],i,j]+PCHN[CSIS[p2],i,j]+m*PCHN[1,i,j]
.
Overview, PauliChain, PCHN, PauliIndex, PauliIndexDelta, DIDelta, PauliChainJoin, PauliChainCombine, PauliChainFactor.
[(CSIS[p] + m) . CSI[a], i, j]
PCHN
[%] PauliChainExpand