Emergence of an Ising critical regime in the clustering of one-dimensional soft matter revealed through string variables

open5noopenF. Mambretti, S. Molinelli, D. Pini, G. Bertaina, D. E. GalliMambretti, F.; Molinelli, S.; Pini, D.; Bertaina, G.; Galli, D. E

Machine-learning of atomic-scale properties based on physical principles

We briefly summarize the kernel regression approach, as used recently in materials modelling, to fitting functions, particularly potential energy surfaces, and highlight how the linear algebra framework can be used to both predict and train from linear functionals of the potential energy, such as the total energy and atomic forces. We then give a detailed account of the Smooth Overlap of Atomic Positions (SOAP) representation and kernel, showing how it arises from an abstract representation of smooth atomic densities, and how it is related to several popular density-based representations of atomic structure. We also discuss recent generalisations that allow fine control of correlations between different atomic species, prediction and fitting of tensorial properties, and also how to construct structural kernels---applicable to comparing entire molecules or periodic systems---that go beyond an additive combination of local environments

A finite field approach to solving the Bethe Salpeter equation

We present a method to compute optical spectra and exciton binding energies of molecules and solids based on the solution of the Bethe-Salpeter equation (BSE) and the calculation of the screened Coulomb interaction in finite field. The method does not require the explicit evaluation of dielectric matrices nor of virtual electronic states, and can be easily applied without resorting to the random phase approximation. In addition it utilizes localized orbitals obtained from Bloch states using bisection techniques, thus greatly reducing the complexity of the calculation and enabling the efficient use of hybrid functionals to obtain single particle wavefunctions. We report exciton binding energies of several molecules and absorption spectra of condensed systems of unprecedented size, including water and ice samples with hundreds of atoms

PyCDFT: A Python package for constrained density functional theory

We present PyCDFT, a Python package to compute diabatic states using constrained density functional theory (CDFT). PyCDFT provides an object-oriented, customizable implementation of CDFT, and allows for both single-point self-consistent-field calculations and geometry optimizations. PyCDFT is designed to interface with existing density functional theory (DFT) codes to perform CDFT calculations where constraint potentials are added to the Kohn-Sham Hamiltonian. Here we demonstrate the use of PyCDFT by performing calculations with a massively parallel first-principles molecular dynamics code, Qbox, and we benchmark its accuracy by computing the electronic coupling between diabatic states for a set of organic molecules. We show that PyCDFT yields results in agreement with existing implementations and is a robust and flexible package for performing CDFT calculations. The program is available at https://github.com/hema-ted/pycdft/.Comment: main text: 27 pages, 6 figures supplementary: 7 pages, 2 figure

Emotion regulation in bank employees. Regulation, antecedents and mediators, and impact on well-being.

none3This study tested to what extent Italian bank employees - working as consultants or at-the-counter - regulate their emotions (Emotional Labor, EL) so as to bring them in line with job requirements, and the frequency, nature, and effects of EL on their well-being. Employees answered questions on personal, work-related and psychological variables. The results showed that EL is a salient aspect of such jobs. Workers performed both Surface Acting and Deep Acting, and frequently reported Emotional Consonance too. SA and EC were negatively related. SA was more likely the higher the number of interactions with clients per day - itself negatively related to interaction duration. EC was more likely the higher the Involvement in the present job role - itself highly negatively related with number of client-interactions. Life Satisfaction was related negatively to SA, and positively related to EC. Emotional labor correlated with reported level of one or more Burnout components; Exhausted and Depersonalized employees reported less Life Satisfaction, and more frequent Negative emotions; Positive emotions were felt more often by Involved employees, and by those who felt Realized in their job. The study confirmed the hypothesis that emotion regulation is significantly associated to various aspects of well-being in bank employees. Keywords- Emotion Regulation; Emotion Labor; Well-Being; Burnout; Affect; Job Involvement; Service Jobs; Bank EmployeesFrontiers in Psychological and Behavioral Science(FPBS) ISSN:2309-012X(Print) ISSN:2309-0138(Online) Emotion Regulation in Bank Employees-Regulation, Antecedents and Mediators, and Impact on Well-Being Vanda Lucia Zammuner, Giulia Gallinari, Cristina Galli Abstract | References Full Paper: PDF (Size:342KB), pp.125-138, Pub. Date: 2013- 07-29, DownLoad: 135 http://www.academicpub.org/fpbs/paperInfo.aspx?PaperID=1491openZammuner; V.L. ; Gallinari; G.; Galli; C.Zammuner, Vanda; Gallinari, G.; Galli, C

Carbon superatom thin films

Assembling clusters on surfaces has emerged as a novel way to grow thin films with targeted properties. In particular, it has been proposed from experimental findings that fullerenes deposited on surfaces could give rise to thin films retaining the bonding properties of the incident clusters. However the microscopic structure of such films is still unclear. By performing quantum molecular dynamics simulations, we show that C_28 fullerenes can be deposited on a surface to form a thin film of nearly defect free molecules, which act as carbon superatoms. Our findings help clarify the structure of disordered small fullerene films and also support the recently proposed hyperdiamond model for solid C_28.Comment: 13 pages, RevTeX, 2 figures available as black and white PostScript files; color PostScript and/or gif files available upon reques

Total energy global optimizations using non orthogonal localized orbitals

An energy functional for orbital based $O(N)$ calculations is proposed, which depends on a number of non orthogonal, localized orbitals larger than the number of occupied states in the system, and on a parameter, the electronic chemical potential, determining the number of electrons. We show that the minimization of the functional with respect to overlapping localized orbitals can be performed so as to attain directly the ground state energy, without being trapped at local minima. The present approach overcomes the multiple minima problem present within the original formulation of orbital based $O(N)$ methods; it therefore makes it possible to perform $O(N)$ calculations for an arbitrary system, without including any information about the system bonding properties in the construction of the input wavefunctions. Furthermore, while retaining the same computational cost as the original approach, our formulation allows one to improve the variational estimate of the ground state energy, and the energy conservation during a molecular dynamics run. Several numerical examples for surfaces, bulk systems and clusters are presented and discussed.Comment: 24 pages, RevTex file, 5 figures available upon reques