diff --git a/g.tex b/g.tex index 59e21bf..92138aa 100644 --- a/g.tex +++ b/g.tex @@ -456,7 +456,7 @@ The time-averaged contribution of the on-state weight can then be easily calcula Details of the implementation of this effective dynamics can be in found in Refs.~\onlinecite{Assaraf_1999B} and \onlinecite{Caffarel_2000}. %=======================================% -\subsection{General domains} +\subsection{Multi-state domains} \label{sec:general_domains} %=======================================% @@ -584,21 +584,25 @@ We then have \qty[ \prod_{k=0}^{p-1} \mel{ I_k }{ \qty(T_{I_k})^{n_k-1} F_{I_k} }{ I_{k+1} } ] G^{(n_p-1),{\cal D}}_{I_p I_N} \end{multline} +where $\delta_{i,j}$ is a Kronecker delta. + This expression is the path-integral representation of the Green's matrix using only the variables $(\ket{I_k},n_k)$ of the effective dynamics defined over the set of domains. -The standard formula derived above, Eq.~\eqref{eq:G} may be considered as the particular case where the domain associated with each state is empty, -In that case, $p=N$ and $n_k=1$ for $k=0$ to $N$ and we are left only with the $p$-th component of the sum, that is, $G^{(N)}_{I_0 I_N} +The standard formula derived above [see Eq.~\eqref{eq:G}] may be considered as the particular case where the domain associated with each state is empty, +In that case, $p=N$ and $n_k=1$ for $0 \le k \le N$ and we are left only with the $p$th component of the sum, that is, $G^{(N)}_{I_0 I_N} = \prod_{k=0}^{N-1} \mel{ I_k }{ F_{I_k} }{ I_{k+1} } $ where $F=T$. To express the fundamental equation for $G$ under the form of a probabilistic average, we write the importance-sampled version of the equation -\be +\begin{multline} \label{eq:Gbart} - {\bar G}^{(N)}_{I_0 I_N}={\bar G}^{(N),{\cal D}}_{I_0 I_N} + + \bar{G}^{(N)}_{I_0 I_N}=\bar{G}^{(N),\cD}_{I_0 I_N} + \sum_{p=1}^{N} - \sum_{|I_1\rangle \notin {\cal D}_{I_0}, \hdots , |I_p\rangle \notin {\cal D}_{I_{p-1}}} - \sum_{n_0 \ge 1} ... \sum_{n_p \ge 1} - \delta(\sum_k n_k=N+1) \Big[ \prod_{k=0}^{p-1} [\frac{\PsiG_{I_{k+1}}}{\PsiG_{I_k}} \langle I_k| T^{n_k-1}_{I_k} F_{I_k} |I_{k+1} \rangle \Big] - {\bar G}^{(n_p-1),{\cal D}}_{I_p I_N}. -\ee + \sum_{\ket{I_1} \notin \cD_{I_0}, \ldots , \ket{I_p} \notin \cD_{I_{p-1}}} + \sum_{n_0 \ge 1} \cdots \sum_{n_p \ge 1} + \\ + \times + \delta_{\sum_k n_k,N+1} \qty{ \prod_{k=0}^{p-1} \qty[ \frac{\PsiG_{I_{k+1}}}{\PsiG_{I_k}} \mel{ I_k }{ \qty(T_{I_k})^{n_k-1} F_{I_k} }{ I_{k+1} } ] } + \bar{G}^{(n_p-1),\cD}_{I_p I_N}. +\end{multline} Introducing the weight \be W_{I_k I_{k+1}} = \frac{\mel{ I_k }{ \qty(T_{I_k})^{n_k-1} F_{I_k} }{ I_{k+1} }}{\mel{ I_k }{ \qty(T^{+}_{I_k})^{n_k-1} F^+_{I_k} }{ I_{k+1} }} @@ -606,20 +610,22 @@ Introducing the weight and using the effective transition probability defined in Eq.~\eqref{eq:eq3C}, we get \be \label{eq:Gbart} - \bar{G}^{(N)}_{I_0 I_N}=\bar{G}^{(N),\cD}_{I_0 I_N}+ \sum_{p=1}^{N} - \bigg \langle - \Big( \prod_{k=0}^{p-1} W_{I_k I_{k+1}} \Big) - {\bar G}^{(n_p-1), {\cal D}}_{I_p I_N} - \bigg \rangle + \bar{G}^{(N)}_{I_0 I_N} = \bar{G}^{(N),\cD}_{I_0 I_N} + \sum_{p=1}^{N} + \expval{ + \qty( \prod_{k=0}^{p-1} W_{I_k I_{k+1}} ) + \bar{G}^{(n_p-1), {\cal D}}_{I_p I_N} + } \ee where the average is defined as -\be +\begin{multline} \expval{F} - = \sum_{|I_1\rangle \notin {\cal D}_{I_0}, \hdots , |I_p\rangle \notin {\cal D}_{I_{p-1}}} + = \sum_{\ket{I_1} \notin \cD_{I_0}, \ldots , \ket{I_p} \notin \cD_{I_{p-1}}} \sum_{n_0 \ge 1} \cdots \sum_{n_p \ge 1} \delta_{\sum_k n_k,N+1} - \prod_{k=0}^{N-1}\cP_{I_k \to I_{k+1}}(n_k-1) F(I_0,n_0;...;I_N,n_N) -\ee + \\ + \times + \prod_{k=0}^{N-1}\cP_{I_k \to I_{k+1}}(n_k-1) F(I_0,n_0;\ldots.;I_N,n_N) +\end{multline} In practice, a schematic DMC algorithm to compute the average is as follows.\\ i) Choose some initial vector $\ket{I_0}$\\ ii) Generate a stochastic path by running over $k$ (starting at $k=0$) as follows.\\