From a095fc0eece3c22bda910b0866ee195e8bc04471 Mon Sep 17 00:00:00 2001 From: filippi-claudia <44236509+filippi-claudia@users.noreply.github.com> Date: Mon, 1 Feb 2021 22:09:14 +0100 Subject: [PATCH] Update QMC.org --- QMC.org | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/QMC.org b/QMC.org index a0ab8f7..15d866d 100644 --- a/QMC.org +++ b/QMC.org @@ -2222,7 +2222,7 @@ gfortran hydrogen.f90 qmc_stats.f90 vmc_metropolis.f90 -o vmc_metropolis To this aim, we use the mixed estimator of the energy: \begin{eqnarray*} - E(\tau) &=& \frac{\langle \psi(tau) | \hat{H} | \Psi_T \rangle}{\langle \psi(tau) | \Psi_T \rangle}\\ + E(\tau) &=& \frac{\langle \psi(\tau) | \hat{H} | \Psi_T \rangle}{\langle \psi(\tau) | \Psi_T \rangle}\\ &=& \frac{\int \psi(\mathbf{r},\tau) \hat{H} \Psi_T(\mathbf{r}) d\mathbf{r}} {\int \psi(\mathbf{r},\tau) \Psi_T(\mathbf{r}) d\mathbf{r}} \\ &=& \frac{\int \psi(\mathbf{r},\tau) \Psi_T(\mathbf{r}) E_L(\mathbf{r}) d\mathbf{r}} @@ -2332,19 +2332,19 @@ gfortran hydrogen.f90 qmc_stats.f90 vmc_metropolis.f90 -o vmc_metropolis - You estimate the energy as - \begin{eqnarray*} - E = \frac{\sum_{k=1}{N_{\rm MC}} E_L(\mathbf{r}_k) W(\mathbf{r}_k, k\delta t)}{\sum_{k=1}{N_{\rm MC}} W(\mathbf{r}_k, k\delta t)} - \end{eqnarray*} + \begin{eqnarray*} + E = \frac{\sum_{k=1}^{N_{\rm MC}} E_L(\mathbf{r}_k) W(\mathbf{r}_k, k\delta t)}{\sum_{k=1}^{N_{\rm MC}} W(\mathbf{r}_k, k\delta t)} + \end{eqnarray*} - The result will be affected by a time-step error (the finite size of $\delta t$) and one - has in principle to extrapolate to the limit $\delta t \rightarrow 0$. This amounts to fitting - the energy computed for multiple values of $\delta t$. + has in principle to extrapolate to the limit $\delta t \rightarrow 0$. This amounts to fitting + the energy computed for multiple values of $\delta t$. - Here, you will be using a small enough time-step and you should not worry about the extrapolation. + Here, you will be using a small enough time-step and you should not worry about the extrapolation. - The accept/reject step (steps 2-5 in the algorithm) is in principle not needed for the correctness of - the DMC algorithm. However, its use reduces significantly the time-step error. + the DMC algorithm. However, its use reduces significantly the time-step error. - PDMC algorithm is less stable than the branching algorithm: it + The PDMC algorithm is less stable than the branching algorithm: it requires to have a value of $E_\text{ref}$ which is close to the fixed-node energy, and a good trial wave function. Its big advantage is that it is very easy to program starting from a VMC