title: Examination of the Feynman-Hibbs Approach in the Study of NeN-Coronene Clusters at Low Temperatures.
abstract: Feynman-Hibbs (FH) effective potentials constitute an appealing approach for investigations of many-body systems at thermal equilibrium since they allow us to easily include quantum corrections within standard classical simulations. In this work we apply the FH formulation to the study of NeN-coronene clusters (N = 1-4, 14) in the 2-14 K temperature range. Quadratic (FH2) and quartic (FH4) contributions to the effective potentials are built upon Ne-Ne and Ne-coronene analytical potentials. In particular, a new corrected expression for the FH4 effective potential is reported. FH2 and FH4 cluster energies and structures-obtained from energy optimization through a basin-hopping algorithm as well as classical Monte Carlo simulations-are reported and compared with reference path integral Monte Carlo calculations. For temperatures T > 4 K, both FH2 and FH4 potentials are able to correct the purely classical calculations in a consistent way. However, the FH approach fails at lower temperatures, especially the quartic correction. It is thus crucial to assess the range of applicability of this formulation and, in particular, to apply the FH4 potentials with great caution. A simple model of N isotropic harmonic oscillators allows us to propose a means of estimating the cutoff temperature for the validity of the method, which is found to increase with the number of atoms adsorbed on the coronene molecule.
authors.affiliation: Instituto de Física Fundamental (IFF-CSIC) , Serrano 123, 28006 Madrid, Spain.
authors.forename: Rocío
authors.initials: R
authors.lastname: Rodríguez-Cantano
authors.affiliation: Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum , 44780 Bochum, Germany.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Pérez de Tudela
authors.affiliation: Instituto de Física Fundamental (IFF-CSIC) , Serrano 123, 28006 Madrid, Spain.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Bartolomei
authors.affiliation: Instituto de Física Fundamental (IFF-CSIC) , Serrano 123, 28006 Madrid, Spain.
authors.forename: Marta I
authors.initials: MI
authors.lastname: Hernández
authors.affiliation: Instituto de Física Fundamental (IFF-CSIC) , Serrano 123, 28006 Madrid, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Campos-Martínez
authors.affiliation: Instituto de Física Fundamental (IFF-CSIC) , Serrano 123, 28006 Madrid, Spain.
authors.forename: Tomás
authors.initials: T
authors.lastname: González-Lezana
authors.affiliation: Instituto de Física Fundamental (IFF-CSIC) , Serrano 123, 28006 Madrid, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Villarreal
authors.affiliation: Departamento de Física and Iudea, Universidad de la Laguna , 38203 Tenerife, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Hernández-Rojas
authors.affiliation: Departamento de Física and Iudea, Universidad de la Laguna , 38203 Tenerife, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Bretón