scholarly journals Ca+ Ions Solvated in Helium Clusters

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3642
Author(s):  
Massimiliano Bartolomei ◽  
Paul Martini ◽  
Ricardo Pérez de Tudela ◽  
Tomás González-Lezana ◽  
Marta I. Hernández ◽  
...  

We present a combined experimental and theoretical investigation on Ca+ ions in helium droplets, HeNCa+. The clusters have been formed in the laboratory by means of electron-impact ionization of Ca-doped helium nanodroplets. Energies and structures of such complexes have been computed using various approaches such as path integral Monte Carlo, diffusion Monte Carlo and basin-hopping methods. The potential energy functions employed in these calculations consist of analytical expressions following an improved Lennard-Jones formula whose parameters are fine-tuned by exploiting ab initio estimations. Ion yields of HeNCa+ -obtained via high-resolution mass spectrometry- generally decrease with N with a more pronounced drop between N=17 and N=25, the computed quantum HeNCa+ evaporation energies resembling this behavior. The analysis of the energies and structures reveals that covering Ca+ with 17 He atoms leads to a cluster with one of the smallest energies per atom. As new atoms are added, they continue to fill the first shell at the expense of reducing its stability, until N=25, which corresponds to the maximum number of atoms in that shell. Behavior of the evaporation energies and radial densities suggests liquid-like cluster structures.

2006 ◽  
Vol 2 (4) ◽  
pp. 221-231
Author(s):  
Nazım Dugan ◽  
Şakir Erkoç

General information about the problem of determining ground-state geometries of atomic clusters has been given. Modified diffusion Monte Carlo (MDMC) method which was recently developed for this problem has been reviewed. A technique, called the rotation operation, has been proposed to escape from local minima. Information about empirical potential energy functions, used in the computations, has been given. Binding energy results for Zn n Cd m and (AlTiNi) n clusters obtained by the combination of the MDMC method and the rotation operation have been presented and these results have been compared with the molecular dynamics (MD) results. Efficiency of the method has been investigated by comparing the results and the computation times with the results of the single walker MDMC method - rotation operation combination.


2020 ◽  
Author(s):  
Marc Riera ◽  
Alan Hirales ◽  
Raja Ghosh ◽  
Francesco Paesani

<div> <div> <div> <p>Many-body potential energy functions (PEFs) based on the TTM-nrg and MB-nrg theoretical/computational frameworks are developed from coupled cluster reference data for neat methane and mixed methane/water systems. It is shown that that the MB-nrg PEFs achieve subchemical accuracy in the representation of individual many-body effects in small clusters and enables predictive simulations from the gas to the liquid phase. Analysis of structural properties calculated from molecular dynamics simulations of liquid methane and methane/water mixtures using both TTM-nrg and MB-nrg PEFs indicates that, while accounting for polarization effects is important for a correct description of many-body interactions in the liquid phase, an accurate representation of short-range interactions, as provided by the MB-nrg PEFs, is necessary for a quantitative description of the local solvation structure in liquid mixtures. </p> </div> </div> </div>


1985 ◽  
Vol 56 (4) ◽  
pp. 839-851 ◽  
Author(s):  
J.N. Murrell ◽  
W. Craven ◽  
M. Vincent ◽  
Z.H. Zhu

1997 ◽  
Vol 73 (3) ◽  
pp. 1281-1287 ◽  
Author(s):  
M. Balsera ◽  
S. Stepaniants ◽  
S. Izrailev ◽  
Y. Oono ◽  
K. Schulten

2004 ◽  
Vol 36 (2) ◽  
pp. 161-165 ◽  
Author(s):  
Francisco M. Fernández ◽  
Eduardo A. Castro

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