diff --git a/Manuscript/rsdft-cipsi-qmc.tex b/Manuscript/rsdft-cipsi-qmc.tex index 519eece..dbad796 100644 --- a/Manuscript/rsdft-cipsi-qmc.tex +++ b/Manuscript/rsdft-cipsi-qmc.tex @@ -531,14 +531,14 @@ starting from $\mu=0$ (\ie, the KS determinant), the FN-DMC error is reduced continuously until it reaches a minimum for an optimal value of $\mu$ (which is obviously basis set and functional dependent), and then the FN-DMC error raises until it reaches the $\mu=\infty$ limit (\ie, the FCI wave function). -For instance, with respect to the fixed-node energy associated with the srPBE/VDZ-BFD trial wave function at $\mu=\infty$, +For instance, with respect to the fixed-node energy associated with the RS-DFT-CIPSI(srPBE/VDZ-BFD) trial wave function at $\mu=\infty$, one can obtain a lowering of the FN-DMC energy of $2.6 \pm 0.7$~m\hartree{} with an optimal value of $\mu=1.75$~bohr$^{-1}$. This lowering in FN-DMC energy is to be compared with the $3.2 \pm 0.7$~m\hartree{} gain in FN-DMC energy between the KS wave function ($\mu=0$) and the FCI wave function ($\mu=\infty$). When the basis set is improved, the gain in FN-DMC energy with respect to the FCI trial wave function is reduced, -and the optimal value of $\mu$ is slightly shifted towards large $\mu$. +and the optimal value of $\mu$ is slightly shifted towards large $\mu$ as expected. Last but not least, the nodes of the wave functions $\Psi^\mu$ obtained with the srLDA functional give very similar FN-DMC energies with respect to those obtained with srPBE, even if the @@ -547,7 +547,7 @@ tens of m\hartree{}. Accordingly, all the RS-DFT calculations are performed with the srPBE functional in the remaining of this paper. Another important aspect here is the compactness of the trial wave functions $\Psi^\mu$: -at $\mu=1.75$~bohr$^{-1}$, $\Psi^{\mu}$ has \textit{only} $54\,540$ determinants at the srPBE/VDZ-BFD level, while the FCI wave function contains $200\,521$ determinants (see Table \ref{tab:h2o-dmc}). Even at the srPBE/VTZ-BFD level, we observe a reduction by a factor two in the number of determinants between the optimal $\mu$ value and $\mu = \infty$. +at $\mu=1.75$~bohr$^{-1}$, $\Psi^{\mu}$ has \textit{only} $54\,540$ determinants at the RS-DFT-CIPSI(srPBE/VDZ-BFD) level, while the FCI wave function contains $200\,521$ determinants (see Table \ref{tab:h2o-dmc}). Even at the RS-DFT-CIPSI(srPBE/VTZ-BFD) level, we observe a reduction by a factor two in the number of determinants between the optimal $\mu$ value and $\mu = \infty$. The take-home message of this first numerical study is that RS-DFT-CIPSI trial wave functions can yield a lower fixed-node energy with more compact multi-determinant expansion as compared to FCI. This is a key result of the present study.