Transition state discovery via application of string methods has been researched on two fronts. The first front involves development of a new string method, named the Searching String method, while ...the second one aims at estimating transition states from a discretized reaction path. The Searching String method has been benchmarked against a number of previously existing string methods and the Nudged Elastic Band method. The developed methods have led to a reduction in the number of gradient calls required to optimize a transition state, as compared to existing methods. The Searching String method reported here places new beads on a reaction pathway at the midpoint between existing beads, such that the resolution of the path discretization in the region containing the transition state grows exponentially with the number of beads. This approach leads to favorable convergence behavior and generates more accurate estimates of transition states from which convergence to the final transition states occurs more readily. Several techniques for generating improved estimates of transition states from a converged string or nudged elastic band have been developed and benchmarked on 13 chemical test cases. Optimization approaches for string methods, and pitfalls therein, are discussed.
Single d-metal atoms on oxygen defects Fs and Fs + of the MgO(001) surface were studied theoretically. We employed an accurate density functional method combined with cluster models, embedded in an ...elastic polarizable environment, and we applied two gradient-corrected exchange-correlation functionals. In this way, we quantified how 17 metal atoms from groups 6−11 of the periodic table (Cu, Ag, Au; Ni, Pd, Pt; Co, Rh, Ir; Fe, Ru, Os; Mn, Re; and Cr, Mo, W) interact with terrace sites of MgO. We found bonding with Fs and Fs + defects to be in general stronger than that with O2- sites, except for Mn-, Re-, and Fe/Fs complexes. In M/Fs systems, electron density is accumulated on the metal center in a notable fashion. The binding energy on both kinds of O defects increases from 3d- to 4d- to 5d-atoms of a given group, at variance with the binding energy trend established earlier for the M/O2- complexes, 4d < 3d < 5d. Regarding the evolution of the binding energy along a period, group 7 atoms are slightly destabilized compared to their group 6 congeners in both the Fs and Fs + complexes; for later transition elements, the binding energy increases gradually up to group 10 and finally decreases again in group 11, most strongly on the Fs site. This trend is governed by the negative charge on the adsorbed atoms. We discuss implications for an experimental detection of metal atoms on oxide supports based on computed core-level energies.
We present a novel scheme to calculate electronic g-tensor values of doublet-state systems within a density functional method and discuss the implementation and results of first applications. The ...method employs two-component eigenfunctions of the Kohn−Sham equation where spin−orbit effects are taken into account self-consistently. Therefore, the g-tensor can be treated as first-order property with respect to the perturbation by external magnetic field alone. The Zeeman energy splitting, an inherently relativistic effect, is naturally and transparently determined by the two-component ground-state wave function (Kramers doublet) without invoking virtual states. Abandoning the widely accepted perturbative treatment of the spin−orbit term makes the present method also applicable to molecular systems with considerable spin−orbit interaction. Conceivable improvements of the method performance are proposed and discussed.
We investigated Boettger’s screened nuclear potential approximation for the spin–orbit interaction (SNSO) in the context of the Douglas–Kroll approach to relativistic Kohn–Sham theory. We extended ...the approximation to second-order terms and evaluated it for various atomic and molecular properties (spin–orbit splittings,
g-tensor shifts, bond lengths, vibrational frequencies and binding energies) and compared the SNSO results with those of a self-consistent relativistic treatment of the electron–electron (ee) interaction. The SNSO approximation is comparable in computational effort to the model based on the nuclear potential only, but delivers molecular results that agree well with those of the more exact ee treatment.
Experimental findings imply that edge sites (and other defects) on Pd nanocrystallites exposing mainly (111) facets in supported model catalysts are crucial for catalyst modification via deposition ...of CH x (x = 0−3) byproducts of methanol decomposition. To explore this problem computationally, we applied our recently developed approach to model realistically metal catalyst particles as moderately large three-dimensional crystallites. We present here the first results of this advanced approach where we comprehensively quantify the reactivity of a metal catalyst in an important chemical process. In particular, to unravel the mechanism of how CH x species are formed, we carried out density functional calculations of C−O bond scission in methanol and various dehydrogenated intermediates (CH3O, CH2OH, CH2O, CHO, CO), deposited on the cuboctahedron model particle Pd79. We calculated the lowest activation barriers, ∼130 kJ mol−1, of C−O bond breaking and the most favorable thermodynamics for the adsorbed species CH3O and CH2OH which feature a C−O single bond. In contrast, dissociation of adsorbed CO was characterized as negligibly slow. From the computational result that the decomposition products CH3 and CH2 preferentially adsorb at edge sites of nanoparticles, we rationalize experimental data on catalyst poisoning.
Effective brand management is vital for building the necessary bond between an organization and its consumers. LG Electronics serves as a notable example of a global company that effectively ...communicates its brand in diverse markets. This study focuses on the remarkable case of LG Electronics' LCD Monitors and plasma TV screens to highlight critical elements of effective brand management across the different cultural contexts of the United Kingdom and the Russian Federation. The findings reveal that LG Electronics standardizes part of its logo and slogan in both cultures. However, the company uses different communication strategies in the UK and Russia. Specifically, LG uses a differentiated strategy with regard to both the visual and the written components of its high-involvement print advertisements. However, it uses a mixed strategy of standardized visual and differentiated written components in its low-involvement TV advertisements. These differences in LG Electronics' print and TV advertisement strategies in two diverse cultures augment contemporary brand management research.
Using various two-step strategies, we examined how to accurately locate transition states (TS) of reactions using the example of eight reactions at metal surfaces with 14–33 moving atoms. These ...procedures combined four path-finding methods for locating approximate TS structures (nudged elastic band, standard string, climbing image string, and searching string, using a conjugate gradient or a modified steepest-descent method for optimization and two types of coordinate systems) with subsequent local refinement by two dimer methods. The dimer-Lanczos variant designed for this study required on average 20% fewer gradient calls than the standard dimer method. During the path finding phase, using mixed instead of Cartesian coordinates reduced the numbers of gradient calls on average by an additional 21%, while using a modified steepest-descent method improved that key efficiency criterion on average by 13%. For problematic cases we suggest strategies especially adapted to the problem at hand.
This article investigates nostalgia in post-socialist Russia from a consumer behavior perspective. The research includes the following components: 1) an overview of nostalgia and nostalgia proneness ...as a personality trait among Russians in the context of recent societal changes, 2) an analysis of four categories of nostalgia (personal, interpersonal, cultural, and virtual) and themes in nostalgia experiences provided by Russian respondents, and 3) a discussion of specific stimuli and advertising content in the Russian marketplace designed to evoke individual and collective nostalgia. The major nostalgia themes—specifically, the break-up of the Soviet Union, nature, and food—identified in the Russian responses are related to advertising and marketing elements for Russian products. The article also discusses the implications of consumer nostalgia for marketing and advertising strategy in the post-socialist Russian economy.
Starting with the hypothesis that cross cultural communication competence affects the performance of multicultural teams, we employed the Cross Cultural Communication Competence Model to compare ...American and Russian managers working in multicultural teams. We collected data from 124 upper and middle managers in the United States and the Russian Federation by administering the cross cultural communication competence and the high-performance team questionnaires. Drawing from proven conceptual cultural orientations suggested by Hall, Hofstede, and Javidan and House, we examined how national culture affects team members’ perceptions of cross cultural communication competence. The confirmed hypothesized relationship and salient effects of national culture on cross cultural communication competence led to theoretical and practical implications for multicultural organizational settings.
