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In this paper we present the Open Software Services for Classrooms and Research (OSSCAR) platform. OSSCAR provides an open collaborative environment to develop, deploy and access educational resources in the form of web applications. To minimize efforts in the creation and use of new educational material, it combines software tools that have emerged as standards with custom domain-specific ones. The technical solutions adopted to create and distribute content are described and motivated on the basis of reliability, sustainability, ease of uptake and use. Examples from courses in the domains of physics, chemistry, and materials science are shown to demonstrate the style and level of interactivity of typical applications. The tools presented are easy to use, and create a uniform and open environment exploitable by a large community of teachers, students, and researchers with the goal of facilitating learning and avoiding, when possible, duplication of efforts in creating teaching material. Contributions to expand the educational content of the OSSCAR project are welcome., Comment: 15 pages, 8 figures

6 software modules delivered to the E-CAM repository in the area of quantum dynamics based on user requests and their documentation.

6 software modules delivered to the E-CAM repository in the area of quantum dynamics based on user requests and their documentation.

In this report for Deliverable 3.1 of E-CAM, 6 software modules in quantum dynamics,which are related to the Extended Software Development Workshop (ESDW) held by E-CAM at Maison de la Simulation, Saclay, in July 2016, are presented. The 6 modules are respectively named: SodLib, ChebLib, PhysConst, PotLib, AuXMod, ClassMC. They include codes for exact integrators of quantum dynamics for low dimensional systems, potentials, calculation of quantum time correlation functions, and their documentation. In this report, a short description is written for each module, followed by a link to the respective Merge-Request on the GitLab service of E-CAM. These merge requests contain detailed information about the code development, testing and documentation of the modules.

Vibrational spectroscopy is a fundamental tool to investigate local atomic arrangements and the effect of the environment, provided that the spectral features can be correctly assigned. This can be challenging in experiments and simulations when double peaks are present because they can have different origins. Fermi dyads are a common class of such doublets, stemming from the resonance of the fundamental excitation of a mode with the overtone of another. We present a new, efficient approach to unambiguously characterize Fermi resonances in density functional theory (DFT) based simulations of condensed phase systems. With it, the spectral features can be assigned and the two resonating modes identified. We also show how data from DFT simulations employing classical nuclear dynamics can be post-processed and combined with a perturbative quantum treatment at a finite temperature to include analytically thermal quantum nuclear effects. The inclusion of these effects is crucial to correct some of the qualitative failures of the Newtonian dynamics simulations at a low temperature such as, in particular, the behavior of the frequency splitting of the Fermi dyad. We show, by comparing with experimental data for the paradigmatic case of supercritical CO2, that these thermal quantum effects can be substantial even at ambient conditions and that our scheme provides an accurate and computationally convenient approach to account for them. Published by AIP Publishing.

Quantum thermal bath (QTB) simulations reproduce statistical nuclear quantum effects via a Langevin equation with a colored random force. Although this approach has proven efficient for a variety of chemical and condensed-matter problems, the QTB, as many other semiclassical methods, suffers from zero-point energy leakage (ZPEL). The absence of a reliable criterion to quantify the ZPEL without resorting to demanding comparisons with path integral-based calculations has so far hindered the use of the QTB for the simulation of real systems. In this work, we establish a quantitative connection between ZPEL in the QTB framework and deviations from the quantum fluctuation dissipation theorem (FDT) that can be monitored along the simulation. This provides a rigorous general criterion to detect and quantify the ZPEL without any a priori knowledge of the system under study. We then use this criterion to build an adaptive QTB method that strictly enforces the quantum FDT at all frequencies via an on-the-fly, spectrally resolved fine-tuning of the system bath coupling coefficients. The validity of the adaptive approach is first demonstrated on a simple two-oscillator model. It is then applied to two more realistic problems: the description of the vibrational properties of a model aluminum crystal at low temperature and the simulation of the liquid-solid phase transition in a 13-atom neon cluster. In both systems, the standard QTB results are strongly altered by the ZPEL, which can be essentially eliminated using the adaptive approach.

We present a study, via experiments and exploratory molecular dynamics simulations, of self aggregation in cylindrical nanostructures obtained experimentally by combining high resolution electron beam lithography with electroless silver deposition. This process is key to the fabrication of a nanolens device, where a strong surface enhancement can be exploited for Raman spectroscopy. In order to investigate the process, we introduce a simple theoretical model and compare the results of simulations with the fabricated silver nanostructures during the growth phase. Our simulations qualitatively agree with the experiments and allow a general characterization of the process at length scales smaller than those easily accessible by microscopy. We identify a geometrical parameter, the aspect ratio of the cylinder, that relates two different types of growth with different characteristics and, possibly, different Raman enhancements.