An analysis of van der Waals density functional components: Binding and corrugation of benzene and C60 on boron nitride and graphene

The adsorption of benzene and C60 on graphene and boron nitride (BN) is studied using density functional theory with the non-local correlation functional vdW-DF. By comparing these systems we can systematically investigate their adsorption nature and differences between the two functional versions vdW-DF1 and vdW-DF2. The bigger size of the C60 molecule makes it bind stronger to the surface than benzene, yet the interface between the molecules and the sheets are similar in nature. The binding separation is more sensitive to the exchange variant used in vdW-DF than to the correlation version. This result is related to the exchange and correlation components of the potential energy curve (PEC). We show that a moderate dipole forms for C60 on graphene, unlike for the other adsorption systems. We find that the corrugation is very sensitive to the variant or version of vdW-DF used, in particular the exchange. Further, we show that this sensitivity arise indirectly through the shift in binding separation caused by changing vdW-DF variant. Based on our results, we suggest a concerted theory-experiment approach to assess the exchange and correlation contributions to physisorption. Using DFT calculations, the corrugation can be linked to the optimal separation, allowing us to extract the exchange-correlation part of the adsorption energy. Molecules with same interfaces to the surface, but different geometries, can in turn cast light on the role of van der Waals forces.Comment: 16 page

An exchange functional that tests the robustness of the plasmon description of the van der Waals density functional

Is the plasmon description within the non-local correlation of the van der Waals density functional by Dion and coworkers (vdW-DF1) robust enough to describe all exchange-correlation components? To address this question, we design an exchange functional, termed LV-PW86r based on this plasmon description as well as recent analysis on exchange in the large $s$-regime. In the regime with reduced gradients $s=|\nabla n|/2n k_{\rm F}(n)$ smaller than $\approx 2.5$, dominating the non-local correlation part of the binding energy, the enhancement factor $F_x(s)$ closely resembles the Langreth-Vosko screened exchange. In the $s$-regime beyond, dominated by exchange, $F_x(s)$ passes smoothly over to the revised Perdew-Wang-86 form. Our tests indicate that vdW-DF1(LV-PW86r) produces accurate separations and binding energies of the S22 data set of molecular dimers as well as accurate lattice constants of layered materials and tightly-bound solids. These results suggest that vdW-DF1 has a good plasmon description in the low-to-moderate $s$-regime

Reactions to reading “Remaining consistent with method? An analysis of grounded theory research in accounting”: A comment on Gurd

Purpose: The present paper is a comment on Gurd's paper published in QRAM on the use of grounded theory in interpretive accounting research. Methodology: Like Gurd, we conducted a bibliographic study on prior pieces of research claiming the use of grounded theory. Findings: We found a large diversity of ways of doing grounded theory. There are as many ways as articles. Consistent with the spirit of grounded theory, the field suggested the research questions, methods and verifiability criteria. From the same sample as Gurd, we arrived at different conclusions. Research limitations: In our research, we did not verify the consistency of claims with grounded theory. We took for granted that they had understood and made operational the suggestions of the founders of the method. Practical implications: The four canons of grounded theory can be considered as reference marks rather than as the rules of the method. Accordingly, the researcher is free to develop his own techniques and procedures. Originality/Value of the paper: This paper stimulates debates on grounded theory based research. On the other hand, it conveys the richness and the variety of interpretive research. Two similar studies, using similar samples and methods arrive at different (divergent) conclusions.grounded theory, interpretive research

Management control system in public administration: beyond rational myths

The implementation of management control devices in the public sector is a very difficult challenge, especially if these devices come from private sector. Through two case studies, this paper analyses how two public organizations have implemented management control systems. We point out that both public organizations studied have developed a complex set of practices around their management control systems. Despite some apparent failures, the implemented systems are not merely myths about the running of public organizations, but instead produced some unanticipated effects.

Rhetoric and the fate of budgeting.

This study focuses on the roles of rhetoric and of the various actors in institutionalisation and deinstitutionalisation attempts. Our paper jointly investigates the process whereby budgeting became institutionalised between 1930 and 1960 and the attempts of the CAM-I to deinstitutionalise it from 1990. Paradoxically, the same two arguments have been used to support the institutionalisation of and the attempts to deinstitutionalise budgets. Firstly, in the 1930’s the turbulence of the environment is used a rhetorical argument to support the implementation of budgeting. Since 1990, the turbulence of the environment has generated a feeling that budgeting should be abandoned. Secondly in the 1930’s and 1950’s budgets contributed to the emancipation of managers, while since 1990 they have been deemed as rigid frameworks preventing managers from acting freely. These contradictions reveal that we can not explain such changes by the rhetorical schemes alone. The network of actors in which these schemes are embedded has a large part in the influence of rhetoric in the change from one institutional order to another. It is particularly the actors to whom these rhetorical schemes are addressed which give them their meanings. Finally, the similarities between the rhetoric used can be explained if we analyse it as the means to transcend the fluctuating contradictions of institutional logics.Budget; managerial concepts; deinstitutionalisation; institutionalisation;

Management control system in public administration: beyond rational myths.

The implementation of management control devices in the public sector is a very difficult challenge, especially if these devices come from private sector. Through two case studies, this paper analyses how two public organizations have implemented management control systems. We point out that both public organizations studied have developed a complex set of practices around their management control systems. Despite some apparent failures, the implemented systems are not merely myths about the running of public organizations, but instead produced some unanticipated effects.contrôle de gestion; secteur public; Management public; pilotage de la performance;

Fabricating management practices : "Responsible Care" and Corporate Social Responsibility.

Purpose this study focuses on the policy of Corporate Social Responsibility (CSR) launched in the chemical industry in the 1980s and known as “Responsible Care”. The debate surrounding this issue prompts us to question the ever-changing nature of this policy and the way to measure the performance achieved. Methodology Our findings are drawn from analysis of a double set of data including a longitudinal survey and a current case study. Blending these two data sets allows a better understanding of the ongoing building process of “Responsible Care” and, more broadly, of corporate social responsibility. Findings this paper asserts that, contrary to the common wisdom developed in research, companies do not simply react to stakeholder pressure. Companies autonomously develop ways to protect their environment and so contribute to changing Society's expectations. Thus, performance cannot be read without a dynamic perspective in mind. Research limitations/implications Our findings lead us to reconsider the assessment of companies' sustainable performances by taking into account the fabricating process of sustainable activities. The main limitation of this research stems from the single unit of analysis considered. Broader studies will be necessary to enrich our understanding of corporate policies. Originality/value of the paper Our paper stands apart from the traditional view of organizations as cynical actors and attempts to provide a more complex picture of the behaviours observed.Performance management; Performance measurement; “Responsible Care”; Corporate Social Responsibility;

Rings sliding on a honeycomb network: Adsorption contours, interactions, and assembly of benzene on Cu(111)

Using a van der Waals density functional (vdW-DF) [Phys. Rev. Lett. 92, 246401 (2004)], we perform ab initio calculations for the adsorption energy of benzene (Bz) on Cu(111) as a function of lateral position and height. We find that the vdW-DF inclusion of nonlocal correlations (responsible for dispersive interactions) changes the relative stability of eight binding-position options and increases the binding energy by over an order of magnitude, achieving good agreement with experiment. The admolecules can move almost freely along a honeycomb web of "corridors" passing between fcc and hcp hollow sites via bridge sites. Our diffusion barriers (for dilute and two condensed adsorbate phases) are consistent with experimental observations. Further vdW-DF calculations suggest that the more compact (hexagonal) Bz-overlayer phase, with lattice constant a = 6.74 \AA, is due to direct Bz-Bz vdW attraction, which extends to ~8 \AA. We attribute the second, sparser hexagonal Bz phase, with a = 10.24 \AA, to indirect electronic interactions mediated by the metallic surface state on Cu(111). To support this claim, we use a formal Harris-functional approach to evaluate nonperturbationally the asymptotic form of this indirect interaction. Thus, we can account well for benzene self-organization on Cu(111).Comment: 13 pages, 7 figures, 3 tables, submitted for publication Accepted for publication in Phys. Rev. B. This version contains improved notation (with corresponding relabeling of figures), very small corrections to some tabulated values, and corrections concerning lattice lengths and subsequent discussion of commensurability of unit-cell dimension

High Current Diffusion Type Diodes at Cryogenic Temperatures for the LHC Superconducting Magnet Protection

High-current by-pass diodes are required for the protection of the superconducting magnets for the Large Hadron Collider LHC at CERN . These diodes are at liquid helium tem-perature and will be exposed to irradiation. With the re-location of the by-pass diodes for the main dipoles underneath the iron yoke and of those for the quadrupoles at the bottom of the cryostat the new estimations for the irradiation dose amounts to about 30 Gy and a neutron fluence of about 1.5 x 1011 n/cm2 for the dipole di-odes and about 100 Gy and5 x 1011 n/cm2 for the quadrupole diodes during 10 years. These relatively low doses may allow the use of diffusion type diodes in-stead of epitaxial diodes. The electrical characteristics of several diodes were measured at temperatures in the range between 1.8K and 300K. Diffu-sion type diodes from three manufacturers were submitted to high current endurance tests in liquid helium. Electrical characteristics and temperatures were measured versus time and showed acceptable results. First irradiation tests show that modified diffusion diodes can be used at least for the dipole by-pass