Computational details of PIMD using i-PI

paper_UAR.tex

@@ -163,7 +163,7 @@ All the energy minima for (H$_2$O)$_{n=3-7}$UH$^+$, have already been obtained i
 {\bf QM/MM method was used to describe the collision process of uracil protonated water cluster (QM) and Argon atom (MM) in the developed deMonNano code.\cite{Warshel1976}  Wrong reference, I prefere to put this in the PES exploration section see above} In the dynamics collision calculation, a Fermi distribution (Fermi temperature 2000 K) was applied to determine the molecular orbital occupations. It can avoid the oscillation problems during the search for a self-consistent solution, often appearing when DFTB energy for dissociated or close to dissociation system was calculated, which allows to recover the continuity in energy and gradients in the case of level crossing. \cite{Kukk2015} {\bf 
 A bit of reordering  : First describe in the right order what is a collsiion : 1=thermalistion 2=send the Argon 3=collect the results (fragments) Second, say what and how it is repeated : change in the impact parameter, 600 dynamics} In the dynamics collision simulation, at the time of 200 fs, the Argon atom was given a velocity (0.0589 Å·fs$^{-1}$) corresponding to the 7.2 eV center of mass collision energy used in the experiment. \cite{Braud2019}. A series of dynamics collision simulation models were generated according to the distance between collision position and the center of size of the cluster. 600 dynamics collision simulations were performed every 0.5 Å from the center of size of each obtained lowest-energy cluster (H$_2$O)$_{n=3-7, 12}$UH$^+$ at molecular dynamics (MD) bath temperature 25 K. {\bf in the following I think you speak about the distance which is actually the impact parameter ... } In case missing any collision, we set the biggest distance between collision position and the center of size of the cluster to be (R + 1) Å rather than the cluster radius R. So totally 600(2R + 3) {\bf it is not clear where this 2R+3 comes from}  simulations were calculated. Owing to cluster was set to rotate regularly during the generation of the models, the Ar atom can collide at almost all the possible positions of the cluster. {\bf Rotateds regularly implies a motion which is not the case here. The target was randomly rotated to to allow for all possible collision point on the cluster} The total simulation time was divided into 600(2R + 3)  segments of 15 ps duration for each {\bf remove  (H$_2$O)$_{n=3-7, 12}$UH$^+$ replace by parent cluster}. After the dynamics collision computation ends of every segment, the geometry of the system was analyzed to detect the possible fragments. A dissociation was defined to arise when the smallest distance between the atoms of two fragments is larger than a given critical distance {\bf , typically} 5.0 Å.
 
-\blue{i-PI?}
+\blue{In order to see the impact of nuclear quantum effects (NQEs) on the localization of the proton after collision we also performed path integral molecular dynamics (PIMD). To do so i-PI 2.0 \cite{i-PI2.0} has been interfaced with deMonNano. Following a client-server model, i-PI handles the propagation of the nuclear motion within the ring polymer approach using the interatomic forces computed by deMonNano. The SCC-DFTB parameters for the calculation of potential energy and forces are the same as before. The dynamics are performed in the micro-canonical ensemble using 16 beads. Again, an initial velocity of 0.0589 Å·fs$^{-1}$ was given to the Argon. The initial velocities of the other atoms were randomly distributed following a Maxwell-Boltzmann distribution at 50 K (so the temperature of the cluster obtained from the kinetic energy is 25 K) and the integration time step was 0.5 fs.}