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Pierre-Francois Loos 2020-08-07 14:56:28 +02:00
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Manuscript/rsdft-cipsi-qmc.tex
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@ -61,6 +61,11 @@
\begin{abstract}
By combining density-functional theory (DFT) and wave function theory (WFT) via the range separation (RS) of the interelectronic Coulomb operator, we obtain accurate fixed-node diffusion Monte Carlo (FN-DMC) energies with compact multideterminant trial wave functions.
These compact trial wave functions are generated via the diagonalization of the RS-DFT Hamiltonian.
In particular, we combine here short-range correlation functionals with selected configuration interaction (SCI).
As the WFT method is relieved from describing the short-range part of the correlation hole around the electron?electron coalescence points, the number of determinants in the trial wave function required to reach a given accuracy is significantly reduced as compared to a conventional SCI calculation.
\titou{T2: work in progress.}
\end{abstract}
\maketitle
@ -143,7 +148,7 @@ FN-DMC.\cite{Petruzielo_2012}
Another approach consists in considering the FN-DMC method as a
\emph{post-FCI method}. The trial wave function is obtained by
approaching the FCI with a selected configuration interaction (sCI)
approaching the FCI with a selected configuration interaction (SCI)
method such as CIPSI for instance.\cite{Giner_2013,Caffarel_2016_2}
\titou{When the basis set is increased, the trial wave function gets closer
to the exact wave function, so the nodal surface can be systematically
@ -688,8 +693,8 @@ functions. But ultimately the exact energy will be reached.
In the context of selected CI calculations, when the variational energy is
extrapolated to the FCI energy\cite{Holmes_2017} there is no
size-consistency error. But when the truncated sCI wave function is used
as a reference for post-Hartree-Fock methods such as sCI+PT2
size-consistency error. But when the truncated SCI wave function is used
as a reference for post-Hartree-Fock methods such as SCI+PT2
or for QMC calculations, there is a residual size-consistency error
originating from the truncation of the wave function.