A detailed description of the mechanism underlying chemical interface damping (CID) in silver nanoclusters is presented. The effect of adsorbates on the surface plasmon excitation in silver nanoclusters is explored by means of a method based on time-dependent self-consistent charge density functional tight binding (TD-SCC-DFTB). By using this tool, we have calculated the homogeneous line width of the surface plasmon resonance (SPR) band for both naked and capped silver nanoclusters. A new picture explaining the decreased lifetime of the surface plasmon excitations is provided, in which coupling between particles states via adsorbate states enhances the natural dephasing mechanism of the surface plasmon excitation. To the best of our knowledge, this is the first report that addresses this topic from a fully atomistic time-dependent approach considering nanosized particles.

In the last thirty years, the study of plasmonic properties of noble metal nanostructures has become a very dynamic research area. The design and manipulation of matter in the nanometric scale demand a deep understanding of the underlying physico-chemical processes that operate in this size regimen. Here, a fully atomistic study of the spectroscopic and photodynamic properties of different icosahedral silver and gold nanoclusters have been carried out by using Time-Dependent Density Functional Tight-Binding (TD-DFTB) model. Optical absorption spectra of different icosahedral silver and gold nanoclusters of diameters between 1 and 4 nanometers has been simulated. Furthermore, the energy absorption process have been quantified by means of calculating a fully quantum absorption cross-section using the information contained in the reduced single-electron density matrix. This approach allows us take into account for the quantum confinement effects dominating in this size regime. Likewise, the plasmon-induced hot-carrier generation process under laser illuminations have been explored from a fully dynamical perspective. We have found noticeable differences in the energy absorption mechanisms and the plasmon-induced hot-carrier generation process in both metals which can be explained by their respective electronic structures.These difference can be attributed to the existence of ultra-fast electronic dissipation channels in gold nanoclusters that are absented in silver nanoclusters. To the best of our knowledge, this is the first report that addresses this topic from a real time fully atomistic time-dependent approach.

The thermal stability of the silver oxide particles (Ag 2 O)/metallic silver nanoparticles (AgNPs) system in aqueous and gaseous environments is investigated with UV-Visible spectroscopy, TEM, SEM and DLS as characterisation techniques, and with calculations using electromagnetic theory. Thermal decomposition of aqueous Ag 2 O colloids to produce AgNPs is conclusively demonstrated and used as a base reaction to produce clean AgNPs without any external reducing agent. Such a spontaneous character of Ag 2 O decomposition in alkaline aqueous/water-enriched environments at room temperature makes the formation of silver oxide films on silver nanoparticles/nanostructures unlikely, keeping the silver surface oxide-free, a crucial feature in determining the silver catalytic and Raman enhancing properties. The synthetic suitability of this reaction to develop new routes to produce AgNPs is explored by analyzing the effect of temperature, complexing agents, and environment polarity on the AgNPs size/shape control. Thermal decomposition of Ag 2 O colloids in aqueous/ water-enriched environments offers the possibility to produce AgNPs at low cost, with easy, clean, safe and green chemistry procedures.

We present the first real-time atomistic simulation on the quantum dynamics of icosahedral silver nanoparticles under strong laser pulses, using time dependent density functional theory (TDDFT) molecular dynamics. We identify the emergence of sub-picosecond breathing-like radial oscillations starting immediately after laser pulse excitation, with increasing amplitude as the field intensity increases. The ultrafast dynamic response of nanoparticles to laser excitation points to a new mechanism other than equilibrium electron-phonon scattering previously assumed, which takes a much longer timescale. A sharp weakening of all bonds during laser excitation is observed, thanks to plasmon damping into excited electrons in anti-bonding states. This sudden weakening of bonds leads to a uniform expansion of the nanoparticles and launches coherent breathing oscillations.

In the last decades, theoretical and experimental studies of nanostructured materials have gathered the efforts of a big slice of the scientific community. Light−nanostructure interaction has been a preponderant research topic fueled by the interest in the plasmonic properties of metallic nanostructures. More recently, the study of plasmon-induced hot carrier generation has drawn the attention of scientists because of their potential application in optoelectronics, photovoltaics, and photocatalysis. In this contribution, we study the real-time electronic dynamics associated with the generation of hot carriers in silver and gold nanoparticles focusing on their energy distribution and atomic shell population/depopulation dynamics. Revisiting our previous results from the perspective of a generalized 2D correlation analysis paves the way to disentangle complex dynamic outcomes, such as the dissipation of the sp-band energy absorbed during plasmonic excitation. We show that this mechanism is founded on the dynamic cross-correlation between sp-band and d-band electronic populations.

The scouting of alternative plasmonic materials able to enhance and extend the optical properties of noble metal nanostructures is on the rise. Aluminum is endowed with a set of interesting properties which turn it into an attractive plasmonic material. Here we present the optical and electronic features of different aluminum nanostructures stemming from a multilevel computational study. Molecular Dynamics (MD) simulations using a reactive force field (ReaxFF), carefully validated with Density Functional Theory (DFT), were employed to mimic the oxidation of icosahedral aluminum nanoclusters. Resulting structures with different oxidation degrees were then studied through the Time-Dependent Density Functional Tight Binding (TD-DFTB) method. A similar approach was used in aluminum nanoclusters with a disordered structure to study how the loss of crystallinity affects the optical properties. To the best of our knowledge, this is the first report that addresses this issue from the fully atomistic time-dependent approach by means of two different and powerful simulation tools able to describe quantum and physicochemical properties associated with nanostructured particles.

<div>Ribulose 1,5-bisphosphate carboxylase-oxygenase (RuBisCO) is the main enzyme involved in atmospheric carbon dioxide (CO₂) fixation in the biosphere. This enzyme catalyses a set of five chemical steps that take place in the same active-site within magnesium (II) coordination sphere. Here, a set of electronic structure benchmark calculations have been carried out on a reaction path proposed by Gready <i>et al.</i> by means of the projector-based embedding approach. Activation and reaction energies for all main steps catalyzed by RuBisCO have been calculated at the MP2, SCS-MP2, CCSD and CCSD(T)/aug-cc-pVDZ and cc-pVDZ levels of theory. </div><div><br></div><div>The treatment of the magnesium cation with post-HF methods is explored to determine the nature of its involvement in the mechanism. With the high-level ab initio values as a reference, we tested the performance of a set of density functional theory (DFT) exchange-correlation (xc) functionals in reproducing the reaction energetics of RuBisCO carboxylase activity on a set of model fragments. Different DFT xc-functionals show large variation in activation and reaction energies. Activation and reaction energies computed at the B3LYP level are close to the reference SCS-MP2 results for carboxylation, hydration and protonation reactions.</div><div><br></div><div>However, for the carbon-carbon bond dissociation reaction, B3LYP and other functionals give results that differ significantly from the ab initio reference values. The results show the applicability of the projector-based embedding approach to metalloenzymes. This technique removes the uncertainty associated with the selection of different DFT xc-functionals and so can overcome some of inherent limitations of DFT calculations, complementing and potentially adding to modelling of enzyme reaction mechanisms with DFT methods.</div>

In the last thirty years, the study of plasmonic properties of noble metal nanostructures has become a very dynamic research area. The design and manipulation of matter in the nanometric scale demand a deep understanding of the underlying physico-chemical processes that operate in this size regimen. Here, a fully atomistic study of the spectroscopic and photodynamic properties of different icosahedral silver and gold nanoclusters have been carried out by using Time-Dependent Density Functional Tight-Binding (TD-DFTB) model. Optical absorption spectra of different icosahedral silver and gold nanoclusters of diameters between 1 and 4 nanometers has been simulated. Furthermore, the energy absorption process have been quantified by means of calculating a fully quantum absorption cross-section using the information contained in the reduced single-electron density matrix. This approach allows us take into account for the quantum confinement effects dominating in this size regime. Likewise, the plasmon-induced hot-carrier generation process under laser illuminations have been explored from a fully dynamical perspective. We have found noticeable differences in the energy absorption mechanisms and the plasmon-induced hot-carrier generation process in both metals which can be explained by their respective electronic structures. These difference can be attributed to the existence of ultra-fast electronic dissipation channels in gold nanoclusters that are absented in silver nanoclusters. To the best of our knowledge, this is the first report that addresses this topic from a real time fully atomistic time-dependent approach. <br>