scholarly journals Multiscale Modeling of Electronic Spectra Including Nuclear Quantum Effects

2021 ◽  
Author(s):  
Peter Feher ◽  
Ádám Madarász ◽  
András Stirling
Keyword(s):  
Electronic Absorption Spectra ◽  
Quantum Effects ◽  
Experimental Spectrum ◽  
Redox States ◽  
Line Shapes ◽  
Gaussian Kernels ◽  
The Individual ◽  
The Impact ◽  
Nuclear Quantum Effects ◽  
Vertical Transitions

<div>Theoretical prediction of electronic absorption spectra without input from experiment is no easy feat as it requires addressing all the factors that affect line shapes. In practice, however, the methodologies are limited to treat these ingredients only to a certain extent. Here we present a multiscale protocol that addresses the temperature, solvent and nuclear quantum effects, anharmonicity and reconstruction of the final spectra from the individual transitions. First, QM/MM molecular dynamics is conducted to obtain trajectories of solute-solvent configurations, from which the corresponding quantum corrected ensembles are generated through the Generalized Smoothed Trajectory Analysis (GSTA). The optical spectra of the ensembles are then produced by calculating vertical transitions using TDDFT with implicit solvation. To obtain the final spectral shapes, the stick spectra from TDDFT are convoluted with Gaussian kernels where the half-widths are determined by a statistically motivated strategy. We have tested our method by calculating the UV-vis spectra of a recently discovered acridine photocatalyst in two redox states and evaluated the impact of each step. Nuclear quantization affects the relative peak intensities and widths, which is necessary to reproduce the experimental spectrum. We have also found that using only the optimized geometry of each molecule works surprisingly well if a proper empirical broadening factor is applied. This is explained by the rigidity of the conjugated chromophore moieties of the selected molecules which are mainly responsible for the excitations in the spectra. In contrast, we have also shown that the molecules are flexible enough to feature anharmonicities that impair the Wigner sampling. </div>

scholarly journals Multiscale Modeling of Electronic Spectra Including Nuclear Quantum Effects

2021 ◽  
Author(s):  
Peter Feher ◽  
Ádám Madarász ◽  
András Stirling
Keyword(s):  
Electronic Absorption Spectra ◽  
Quantum Effects ◽  
Experimental Spectrum ◽  
Redox States ◽  
Line Shapes ◽  
Gaussian Kernels ◽  
The Individual ◽  
The Impact ◽  
Nuclear Quantum Effects ◽  
Vertical Transitions

<div>Theoretical prediction of electronic absorption spectra without input from experiment is no easy feat as it requires addressing all the factors that affect line shapes. In practice, however, the methodologies are limited to treat these ingredients only to a certain extent. Here we present a multiscale protocol that addresses the temperature, solvent and nuclear quantum effects, anharmonicity and reconstruction of the final spectra from the individual transitions. First, QM/MM molecular dynamics is conducted to obtain trajectories of solute-solvent configurations, from which the corresponding quantum corrected ensembles are generated through the Generalized Smoothed Trajectory Analysis (GSTA). The optical spectra of the ensembles are then produced by calculating vertical transitions using TDDFT with implicit solvation. To obtain the final spectral shapes, the stick spectra from TDDFT are convoluted with Gaussian kernels where the half-widths are determined by a statistically motivated strategy. We have tested our method by calculating the UV-vis spectra of a recently discovered acridine photocatalyst in two redox states and evaluated the impact of each step. Nuclear quantization affects the relative peak intensities and widths, which is necessary to reproduce the experimental spectrum. We have also found that using only the optimized geometry of each molecule works surprisingly well if a proper empirical broadening factor is applied. This is explained by the rigidity of the conjugated chromophore moieties of the selected molecules which are mainly responsible for the excitations in the spectra. In contrast, we have also shown that the molecules are flexible enough to feature anharmonicities that impair the Wigner sampling. </div>

scholarly journals On-the-Fly Ring-Polymer Molecular Dynamics Calculations of the Dissociative Photodetachment Process of the Oxalate Anion

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7250
Author(s):  
Yukinobu Takahashi ◽  
Yu Hashimoto ◽  
Kohei Saito ◽  
Toshiyuki Takayanagi
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy ◽  
Quantum Effects ◽  
Experimental Spectrum ◽  
Computational Time ◽  
Oxalate Anion ◽  
Dissociative Photodetachment ◽  
Ring Polymer ◽  
Ring Polymer Molecular Dynamics ◽  
Nuclear Quantum Effects

The dissociative photodetachment dynamics of the oxalate anion, C2O4H− + hν → CO2 + HOCO + e−, were theoretically studied using the on-the-fly path-integral and ring-polymer molecular dynamics methods, which can account for nuclear quantum effects at the density-functional theory level in order to compare with the recent experimental study using photoelectron–photofragment coincidence spectroscopy. To reduce computational time, the force acting on each bead of ring-polymer was approximately calculated from the first and second derivatives of the potential energy at the centroid position of the nuclei beads. We find that the calculated photoelectron spectrum qualitatively reproduces the experimental spectrum and that nuclear quantum effects are playing a role in determining spectral widths. The calculated coincidence spectrum is found to reasonably reproduce the experimental spectrum, indicating that a relatively large energy is partitioned into the relative kinetic energy between the CO2 and HOCO fragments. This is because photodetachment of the parent anion leads to Franck–Condon transition to the repulsive region of the neutral potential energy surface. We also find that the dissociation dynamics are slightly different between the two isomers of the C2O4H− anion with closed- and open-form structures.

Accent Policy and Accent Modification Enterprises as Potential Indicators of Intercultural Power Relations: A Call for an Updated Research Agenda

2013 ◽  
Vol 3 (1) ◽  
pp. 22-33 ◽  
Author(s):  
Brynne D. Ovalle ◽  
Rahul Chakraborty
Keyword(s):  
International Relations ◽  
Identity Construction ◽  
Social Theory ◽  
Power Relations ◽  
Linguistic Diversity ◽  
Cultural Organization ◽  
Using Data ◽  
The Individual ◽  
The Impact ◽  
The Relationship

This article has two purposes: (a) to examine the relationship between intercultural power relations and the widespread practice of accent discrimination and (b) to underscore the ramifications of accent discrimination both for the individual and for global society as a whole. First, authors review social theory regarding language and group identity construction, and then go on to integrate more current studies linking accent bias to sociocultural variables. Authors discuss three examples of intercultural accent discrimination in order to illustrate how this link manifests itself in the broader context of international relations (i.e., how accent discrimination is generated in situations of unequal power) and, using a review of current research, assess the consequences of accent discrimination for the individual. Finally, the article highlights the impact that linguistic discrimination is having on linguistic diversity globally, partially using data from the United Nations Educational, Scientific and Cultural Organization (UNESCO) and partially by offering a potential context for interpreting the emergence of practices that seek to reduce or modify speaker accents.

Investigating the Relationship Between Self-Esteem and Stigma Among Young Adults With History of Suicide Attempts

Crisis ◽  
2016 ◽  
Vol 37 (4) ◽  
pp. 265-270 ◽  
Author(s):  
Meshan Lehmann ◽  
Matthew R. Hilimire ◽  
Lawrence H. Yang ◽  
Bruce G. Link ◽  
Jordan E. DeVylder
Keyword(s):  
Young Adults ◽  
Suicide Attempts ◽  
Self Esteem ◽  
High Risk Population ◽  
High Functioning ◽  
People With Mental Illness ◽  
History Of ◽  
The Individual ◽  
The Impact ◽  
The Relationship

Abstract. Background: Self-esteem is a major contributor to risk for repeated suicide attempts. Prior research has shown that awareness of stigma is associated with reduced self-esteem among people with mental illness. No prior studies have examined the association between self-esteem and stereotype awareness among individuals with past suicide attempts. Aims: To understand the relationship between stereotype awareness and self-esteem among young adults who have and have not attempted suicide. Method: Computerized surveys were administered to college students (N = 637). Linear regression analyses were used to test associations between self-esteem and stereotype awareness, attempt history, and their interaction. Results: There was a significant stereotype awareness by attempt interaction (β = –.74, p = .006) in the regression analysis. The interaction was explained by a stronger negative association between stereotype awareness and self-esteem among individuals with past suicide attempts (β = –.50, p = .013) compared with those without attempts (β = –.09, p = .037). Conclusion: Stigma is associated with lower self-esteem within this high-functioning sample of young adults with histories of suicide attempts. Alleviating the impact of stigma at the individual (clinical) or community (public health) levels may improve self-esteem among this high-risk population, which could potentially influence subsequent suicide risk.

The Role of Threat and Economic Uncertainty in Support for Scottish Independence

2014 ◽  
Vol 23 (1) ◽  
pp. 103-124 ◽  
Author(s):  
Daniel Kopasker
Keyword(s):  
Economic Consequences ◽  
Perceived Threat ◽  
Constitutional Change ◽  
Lack Of Information ◽  
Economic Expectations ◽  
Scottish Independence ◽  
The Individual ◽  
The Impact ◽  
Levels Of Support

Existing research has consistently shown that perceptions of the potential economic consequences of Scottish independence are vital to levels of support for constitutional change. This paper attempts to investigate the mechanism by which expectations of the economic consequences of independence are formed. A hypothesised causal micro-level mechanism is tested that relates constitutional preferences to the existing skill investments of the individual. Evidence is presented that larger skill investments are associated with a greater likelihood of perceiving economic threats from independence. Additionally, greater perceived threat results in lower support for independence. The impact of uncertainty on both positive and negative economic expectations is also examined. While uncertainty has little effect on negative expectations, it significantly reduces the likelihood of those with positive expectations supporting independence. Overall, it appears that a general economy-wide threat is most significant, and it is conjectured that this stems a lack of information on macroeconomic governance credentials.

Laughter on the Fringes

2019 ◽  
Author(s):  
Anna Peterson
Keyword(s):  
The Other ◽  
Literary Canon ◽  
Autobiographical Writing ◽  
Treasure Trove ◽  
Old Comedy ◽  
Other Hand ◽  
Aggressive Humor ◽  
The One ◽  
The Individual ◽  
The Impact

This book examines the impact that Athenian Old Comedy had on Greek writers of the Imperial era. It is generally acknowledged that Imperial-era Greeks responded to Athenian Old Comedy in one of two ways: either as a treasure trove of Atticisms, or as a genre defined by and repudiated for its aggressive humor. Worthy of further consideration, however, is how both approaches, and particularly the latter one that relegated Old Comedy to the fringes of the literary canon, led authors to engage with the ironic and self-reflexive humor of Aristophanes, Eupolis, and Cratinus. Authors ranging from serious moralizers (Plutarch and Aelius Aristides) to comic writers in their own right (Lucian, Alciphron), to other figures not often associated with Old Comedy (Libanius) adopted aspects of the genre to negotiate power struggles, facilitate literary and sophistic rivalries, and provide a model for autobiographical writing. To varying degrees, these writers wove recognizable features of the genre (e.g., the parabasis, its agonistic language, the stage biographies of the individual poets) into their writings. The image of Old Comedy that emerges from this time is that of a genre in transition. It was, on the one hand, with the exception of Aristophanes’s extant plays, on the verge of being almost completely lost; on the other hand, its reputation and several of its most characteristic elements were being renegotiated and reinvented.

Individuality and Beyond

2019 ◽  
Author(s):  
Benedetta Zavatta
Keyword(s):  
Moral Autonomy ◽  
First Line ◽  
Philosophical Interpretation ◽  
Individual Personality ◽  
The World ◽  
Regulative Ideal ◽  
Personal Library ◽  
The Many ◽  
The Individual ◽  
The Impact

Based on an analysis of the marginal markings and annotations Nietzsche made to the works of Emerson in his personal library, the book offers a philosophical interpretation of the impact on Nietzsche’s thought of his reading of these works, a reading that began when he was a schoolboy and extended to the final years of his conscious life. The many ideas and sources of inspiration that Nietzsche drew from Emerson can be organized in terms of two main lines of thought. The first line leads in the direction of the development of the individual personality, that is, the achievement of critical thinking, moral autonomy, and original self-expression. The second line of thought is the overcoming of individuality: that is to say, the need to transcend one’s own individual—and thus by definition limited—view of the world by continually confronting and engaging with visions different from one’s own and by putting into question and debating one’s own values and certainties. The image of the strong personality that Nietzsche forms thanks to his reading of Emerson ultimately takes on the appearance of a nomadic subject who is continually passing out of themselves—that is to say, abandoning their own positions and convictions—so as to undergo a constant process of evolution. In other words, the formation of the individual personality takes on the form of a regulative ideal: a goal that can never be said to have been definitively and once and for all attained.

An Active Learning Approach to Teaching Social Determinants of Health

2020 ◽  
Vol 6 (4) ◽  
pp. 266-273
Author(s):  
Jeanita W. Richardson
Keyword(s):  
Active Learning ◽  
Learning Style ◽  
Social Determinants ◽  
Learning Approach ◽  
Learning Style Preferences ◽  
Open Discussion ◽  
Approach To Teaching ◽  
The Individual ◽  
Style Preferences ◽  
The Impact

This active learning exercise is designed to deconstruct the impact of social determinants through the assumption of randomly selected personas. As an active learning exercise, it provides opportunities for discussion, problem solving, writing, and synthesis, while incorporating multiple learning style preferences. Part 1 involves assessing the individual social determinants at work. Part 2 involves exploring ways said determinants can enhance community health through collaboration. Assumption of personas unlike one’s own facilitates an open discussion of social position and ranges of factors influential to health without potentially evoking a sense of defensiveness associated with personal privilege (or the lack thereof).

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