minor corrections

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Pierre-Francois Loos 2020-08-08 08:59:59 +02:00
parent 6237c3f12a
commit 16c822340d

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@ -23,7 +23,7 @@
\newcommand{\titou}[1]{\textcolor{red}{#1}}
\newcommand{\trashPFL}[1]{\textcolor{red}{\sout{#1}}}
\newcommand{\PFL}[1]{\titou{(\underline{\bf PFL}: #1)}}
\newcommand{\SI}{supplementary material}
\newcommand{\SI}{\textcolor{blue}{supplementary material}}
\newcommand{\mc}{\multicolumn}
\newcommand{\fnm}{\footnotemark}
@ -269,10 +269,10 @@ where
are the singular short-range (sr) part and the non-singular long-range (lr) part, respectively, $\mu$ is the range-separation parameter which controls how rapidly the short-range part decays, $\erf(x)$ is the error function, and $\erfc(x) = 1 - \erf(x)$ is its complementary version.
The main idea behind RS-DFT is to treat the short-range part of the
interaction within KS-DFT, and the long range part within a WFT method like FCI in the present case.
interaction within KS-DFT, and the long-range part within a WFT method like FCI in the present case.
The parameter $\mu$ controls the range of the separation, and allows
to go continuously from the KS Hamiltonian ($\mu=0$) to
the FCI Hamiltonian ($\mu = \infty$).
the FCI Hamiltonian ($\mu \to \infty$).
To rigorously connect WFT and DFT, the universal
Levy-Lieb density functional \cite{Lev-PNAS-79,Lie-IJQC-83} is
@ -295,7 +295,7 @@ electronic energy
},
\end{equation}
with $\hat{T}$ the kinetic energy operator,
$\hat{W}_\text{ee}^{\text{lr}}$ the long-range
$\hat{W}_\text{ee}^{\text{lr},\mu}$ the long-range
electron-electron interaction,
$n_\Psi$ the one-electron density associated with $\Psi$,
and $\hat{V}_{\text{ne}}$ the electron-nucleus potential.
@ -360,12 +360,12 @@ In the outer (macro-iteration) loop (red), at the $k$th iteration, a CIPSI selec
to obtain $\Psi^{\mu\,(k)}$ with the RS Hamiltonian $\hat{H}^{\mu\,(k)}$
parameterized using the current one-electron density $n^{(k)}$.
At each iteration, the number of determinants in $\Psi^{\mu\,(k)}$ increases.
One exits the macro-iteration loop when the absolute energy difference between two successive iterations $\Delta E^{(k)}$ is below a threshold $\tau_1$ that has been set to \titou{???} in the present study.
One exits the outer loop when the absolute energy difference between two successive macro-iterations $\Delta E^{(k)}$ is below a threshold $\tau_1$ that has been set to \titou{???} in the present study.
An inner (micro-iteration) loop (blue) is introduced to accelerate the
convergence of the self-consistent calculation, in which the set of
determinants in $\Psi^{\mu\,(k,l)}$ is kept fixed, and only the diagonalization of
$\hat{H}^{\mu\,(k,l)}$ is performed iteratively with the updated density $n^{(k,l)}$.
The micro-iteration loop is exited when the absolute energy difference between two successive iterations $\Delta E^{(k,l)}$ is below a threshold $\tau_2$ that has been set to \titou{???} in the present study.
The inner loop is exited when the absolute energy difference between two successive micro-iterations $\Delta E^{(k,l)}$ is below a threshold $\tau_2$ that has been here set to \titou{???}.
The convergence of the algorithm was further improved
by introducing a direct inversion in the iterative subspace (DIIS)
step to extrapolate the density both in the outer and inner loops. \cite{Pulay_1980,Pulay_1982}
@ -379,8 +379,8 @@ the final trial wave function $\Psi^{\mu}$ is independent of the starting wave f
\section{Computational details}
\label{sec:comp-details}
\titou{The geometries for the G2 data set are provided as {\SI}.}
For all the systems considered here, experimental geometries have been considered and they have been extracted from the NIST website.
Geometries for each system are reported in the {\SI}.
All the calculations have been performed using Burkatzki-Filippi-Dolg (BFD)
pseudopotentials \cite{Burkatzki_2007,Burkatzki_2008} with the associated double-,
@ -413,6 +413,7 @@ algorithm developed by Assaraf \textit{et al.}, \cite{Assaraf_2000}
with a time step of $5 \times 10^{-4}$ a.u.
\titou{All-electron move DMC?}
\titou{Missing details and references about srLDA and srPBE functionals.}
\section{Influence of the range-separation parameter on the fixed-node
error}
@ -457,19 +458,19 @@ with a time step of $5 \times 10^{-4}$ a.u.
The first question we would like to address is the quality of the
nodes of the wave functions $\Psi^{\mu}$ obtained with an intermediate
range separation parameter (\textit{i.e.} $0 < \mu < +\infty$).
We generated trial wave functions $\Psi^\mu$ with multiple values of
$\mu$, and computed the associated fixed node energy keeping all the
parameters having an impact on the nodal surface fixed.
We considered a weakly correlated molecular systems: the water
range separation parameter (\ie, $0 < \mu < +\infty$).
For this purpose, we consider a weakly correlated molecular system: the water
molecule near its equilibrium geometry.\cite{Caffarel_2016}
We then generate trial wave functions $\Psi^\mu$ for multiple values of
$\mu$, and compute the associated fixed-node energy keeping all the
parameters having an impact on the nodal surface fixed (\titou{such as ??}).
\subsection{Fixed-node energy of $\Psi^\mu$}
\label{sec:fndmc_mu}
From Table~\ref{tab:h2o-dmc} and Fig.~\ref{fig:h2o-dmc},
one can clearly observe that using a FCI trial
wave functions ($\mu = \infty$) give an FN-DMC energies lower
than the energies obtained with a single Kohn-Sham determinant ($\mu=0$):
one can clearly observe that using FCI trial
wave functions ($\mu \to \infty$) give FN-DMC energies lower
than the energies obtained with a single KS determinant ($\mu=0$):
a gain of $3.2 \pm 0.6$~m\hartree{} at the double-zeta level and $7.2 \pm
0.3$~m\hartree{} at the triple-zeta level are obtained.
Coming now to the nodes of the trial wave functions $\Psi^{\mu}$ with