PairExcitationBra file¶
The operators \(B\) to generate the bra pair excited state \(B|\phi\rangle\), used to compute the off-diagonal dynamical Green’s function
where the ket operator \(A\) is given in PairExcitation. If this file is omitted, the ordinary diagonal Green’s function (\(B=A\)) is calculated.
The file format and parameters are the same as the
PairExcitation file; only the keyword for the
number of operators is NPairExcitationBra. An example
(a density operator \(n_{1\uparrow}\) on site 1):
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NPairExcitationBra 1
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======= Pair Excitation Bra ====
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1 0 1 0 1 1.0 0.0
Use rules¶
Headers cannot be omitted; the format and parameters are identical to the PairExcitation file.
The operator written here is \(B\), not \(B^{\dagger}\). The computed quantity is \(\langle\phi|B^{\dagger}(z-H)^{-1}A|\phi\rangle\).
The off-diagonal Green’s function is available only with the shifted BiCG method (
method="CG") andCalcSpec="Normal"(restart/save spectrum modes are not supported together with a bra operator).The ket (PairExcitation) and bra operators must map \(|\phi\rangle\) into the same excited Hilbert sector (the same change of particle number and \(S_z\)). All operators within one file must also share the same sector change. Otherwise the program is terminated.
Supported models: Hubbard, Spin, and SpinGC. (Other models are not yet supported for the off-diagonal Green’s function; the program is terminated for them.)
SingleExcitationBraandPairExcitationBracannot be specified at the same time.
