Interior- and Surface-Bound Excess Electron States in Large Water Cluster Anions

We present the results of mixed quantum/classical simulations on relaxed thermal nanoscale water cluster anions,(H_2O)^-_n, with n=200, 500, 1000 and 8000. By using initial equilibration with constraints, we investigate stable/metastable negatively charged water clusters with both surface-bound and interior-bound excess electron states. Characterization of these states is performed in terms of geometrical parameters, energetics, and optical absorption spectroscopy of the clusters. The calculations provide data characterizing these states in the gap between previously published calculations, and experiments, on smaller clusters and the limiting cases of either an excess electron in bulk water, or an excess electron at an infinite water/air interface. The present results are in general agreement with previous simulations and provide a consistent picture of the evolution of the physical properties of water cluster anions with size over the entire size range, including results for vertical detachment energies and absorption spectra that would signify their presence. In particular, the difference in size dependence between surface-bound and interior-bound state absorption spectra is dramatic, while for detachment energies the dependence is qualitatively the same

Excess Electron Localization Sites in Neutral Water Clusters

We present approximate pseudopotential quantum mechanical calculations of the excess electron states of equilibrated neutral water clusters sampled by classical molecular dynamics simulations. The internal energy of the clusters are representative of those present at temperatures of 200 K and 300 K. Correlated electronic structure calculations are used to validate the pseudopotential for this purpose. We find that the neutral clusters support localized, bound excess electron ground states in about 50 % of the configurations for the smallest cluster size studied (n=20), and in almost all configurations for larger clusters (n>66). The state is always exterior to the molecular frame, forming typically a diffuse surface state. Both cluster size and temperature dependence of energetic and structural properties of the clusters and the electron distribution are explored. We show that the stabilization of the electron is strongly correlated with the pre-existing instantaneous dipole moment of the neutral clusters, and its ground state energy is reflected in the electronic radius. The findings are consistent with electron attachment via an initial surface state. The hypothetical spectral dynamics following such attachment is also discussed

Excess Electron Relaxation Dynamics at Water/Air Interfaces

We have performed mixed quantum-classical molecular dynamics simulations of the relaxation of a ground state excess electron at interfaces of different phases of water with air. The investigated systems included ambient water/air, supercooled water/air, Ih ice/air and an amorphous solid water/air interfaces. The present work explores the possible connections of the examined interfacial systems to finite size cluster anions, and the three-dimensional infinite, fully hydrated electron. Localization site analyses indicate that in the absence of nuclear relaxation the electron localizes in a shallow potential trap on the interface in all examined systems in a diffuse, surface-bound (SB) state. With relaxation, the weakly bound electron undergoes an ultrafast localization and stabilization on the surface with the concomitant collapse of its radius. In the case of the ambient liquid interface the electron slowly (on the 10 ps timescale) diffuses into the bulk to form an interior-bound (IB) state. In each other case, the excess electron persists on the interface in surface-bound (SB) states. The relaxation dynamics occur through distinct SB structures which are easily distinguishable by their energetics, geometries, and interactions with the surrounding water bath. The systems exhibiting the most stable SB excess electron states (supercooled water/air and Ih ice/air interfaces) are identified by their characteristic hydrogen-bonding motifs which are found to contain double acceptor type water molecules in the close vicinity of the electron. These surface states correlate reasonably with those extrapolated to infinite size from simulated water cluster anions

Indexed induction and coinduction, fibrationally.

This paper extends the fibrational approach to induction and coinduction pioneered by Hermida and Jacobs, and developed by the current authors, in two key directions. First, we present a sound coinduction rule for any data type arising as the final coalgebra of a functor, thus relaxing Hermida and Jacobs’ restriction to polynomial data types. For this we introduce the notion of a quotient category with equality (QCE), which both abstracts the standard notion of a fibration of relations constructed from a given fibration, and plays a role in the theory of coinduction dual to that of a comprehension category with unit (CCU) in the theory of induction. Second, we show that indexed inductive and coinductive types also admit sound induction and coinduction rules. Indexed data types often arise as initial algebras and final coalgebras of functors on slice categories, so our key technical results give sufficent conditions under which we can construct, from a CCU (QCE) U : E -> B, a fibration with base B/I that models indexing by I and is also a CCU (QCE)

Quantized time correlation function approach to non-adiabatic decay rates in condensed phase: Application to solvated electrons in water and methanol

A new, alternative form of the golden rule formula defining the non-adiabatic transition rate between two quantum states in condensed phase is presented. The formula involves the quantum time correlation function of the energy gap, of the non-adiabatic coupling, and their cross terms. Those quantities can be inferred from their classical counterparts, determined via MD simulations. The formalism is applied to the problem of the non-adiabatic relaxation of an equilibrated p-electron in water and methanol. We find that, in both solvent, the relaxation is induced by the coupling to the vibrational modes and the quantum effects modify the rate by a factor of 2-10 depending on the quantization procedure applied. The resulting p-state lifetime for a hypothetical equilibrium excited state appears extremely short, in the sub-100 fs regime. Although this result is in contrast with all previous theoretical predictions, we also illustrate that the lifetimes computed here are very sensitive to the simulated electronic quantum gap and to the strongly correlated non-adiabatic coupling

Excess electron solvation in ammonia clusters

We performed a combination of quantum chemical calculations and molecular dynamics simulations to assess the stability of various size ("N" "H" _"3" )_n^- ammonia cluster anions up to n = 32 monomers. In the n = 3 – 8 size range, cluster anions are optimized and the vertical detachment energy of the excess electron (VDE) from increasing size clusters are computed using various level methods including density functional theory (DFT), MP2 and CCSD(T) calculations. These clusters bind the electron in non-branched hydrogen bonding chains in dipole bound states. The VDE increases with size from a few meV up to ~200 meV. The electron binding energy is weaker than in water clusters but comparable to small methanol cluster VDEs. We located the first branched hydrogen bonding cluster that binds the excess electron at n = 7. For larger (n = 8 – 32) clusters we generated cold, neutral clusters by semiempirical and ab initio molecular dynamics (AIMD) simulations, and added an extra electron to selected neutral configurations. VDE calculations on the adiabatic and the relaxed anionic structures suggest that the n = 12 - 32 neutral clusters weakly bind the excess electron. Electron binding energies for these clusters (~ 100 meV) appear to be significantly weaker than extrapolated from experimental data. The observed excess electron states are diffuse and localized outside the molecular frame (surface states) with minor (~1%) penetration to the nitrogen frontier orbitals. Stable minima with excess electron states surrounded by solvent molecules (cavity states) were not found in this size regime

The relationship between internalizing and externalizing symptoms and cultural resilience factors in Indigenous Sami youth from Arctic Norway

The accepted manuscript version of this article is part of Margrethe Bals' doctoral thesis, which is available in Munin at http://hdl.handle.net/10037/2934Objectives. To examine whether enculturation factors, like cultural activities, ethnic pride and native language competence, are related to decreased internalizing and externalizing symptoms in Indigenous Sami youth from Arctic Norway. The impact of self-efficacy on the relationship between enculturation factors and mental health problems was also examined. Study design. Population-based, cross-sectional questionnaire study. Methods. The Norwegian Arctic Adolescent Health Study was conducted among 10th graders in junior high schools in north Norway during 2003–2005. The study sample consisted of 450 Indigenous Sami youth, aged 15–16 years. Internalizing symptoms were measured with the Hopkins Symptom Check List- 10 (HSCL-10), while externalizing symptoms were measured by two subscales of the Strengths and Difficulties Questionnaire (SDQ). Results. For boys, self-efficacy and participation in cultural activities were associated with decreased internalizing symptoms. Additionally, self-efficacy interacted with Sami language competence and cultural activities: when self-efficacy increased, these enculturation factors were related to symptom reduction. For girls, self-efficacy had an independent effect on internalizing symptoms and also strengthened the relationship between participation in cultural activities and reduced externalizing symptoms. Sami language competence was related to the reduction of both internalizing and externalizing symptoms in girls. Conclusions. In the present study, several enculturation factors as well as self-efficacy were identified as potential protective factors against mental health problems. In order to develop theoretical models that explain the mechanisms between cultural resilience and mental health, there is a need for both qualitative studies and longitudinal studies

PERANAN PENYULUH PADA PEMELIHARAAN TERNAK BABI LOKAL DI DESA GUMBO KECAMATAN TIOMNERI KABUPATEN LANNY JAYA

ROLE OF CATTLE PIGS COUNSELORS  MAINTENANCE OF LOCAL DISTRICT IN THE VILLAGE GUMBO TIOMNERI LANNY JAYA REGENCY. The study aims to  determine characteristics and breeders perception toward extension activities in the District Gumbo village Tiomneri Lanny Jaya Regency Research has implemented since December, 1th until January 31th 2018 using survey method.   Twenty two of pig breeders in the village pig farmers Gumbo Tiomneri District of Lanny Jaya Regency  was selected by census as sample of respondents. Data analysis using scale of likert Study results indicated  that  breeders perception of the role of agriculture extension agent  as a motivator and facilitator in the District Gumbo village Tiomneri Lanny Jaya Regency was already optimal, or in other words the role of extension officers in performing their duties was already good. The  process of adoption of technology  by pig farmers in the village of the District Gumbo Tiomneri Lanny Jaya Regency was varied from respondents..The role agriculture counselor as a motivator  has succeed to change the habits of farmers tradition that used to keep cattle in the house where they live (home honai) but by  now farmers have made pig pen outside their house.Keywords: Role of Extension agent,  pigs, Gumbo.