First-principles theory

Flybertsen M S and Louie S G 1985 First-principles theory of quasiparticles Calculation of band gaps in semiconductors and insulators Phys. Rev. Lett. 55 1418... 

On a different note, after some 50 years of intensive research on high-pressure shock compression, there are still many outstanding problems that cannot be solved. For example, it is not possible to predict ab initio the time scales of the shock-transition process or the thermophysical and mechanical properties of condensed media under shock compression. For the most part, these properties must presently be evaluated experimentally for incorporation into semiempirical theories. To realize the potential of truly predictive capabilities, it will be necessary to develop first-principles theories that have robust predictive capability. This will require critical examination of the fundamental postulates and assumptions used to interpret shock-compression processes. For example, it is usually assumed that a steady state is achieved immediately after the shock-transition process. However, due to the fact that... 

A comparison of the predictions for the cavity pair correlation function of some first-principles theories with computer simulation results [72] at a fairly high density has been presented by Stell (see Fig. 2 in Ref. 69). The... 

Stampfl C, KreuzerHJ, Payne SH, PfniirH, Scheffler M. 1999. First-principles theory of surface thermodynamics and kinetics. Phys Rev Lett 83 2993. 

However, useful as it is, ligand field theory is not a predictive first principles theory. Thus, it cannot be used to predict a priori the Mossbauer parameters of a given compound. Yet, the need to do so arises fi equently in Mossbauer spectroscopy. For example, if a reaction intermediate or some other unstable chemical species has been characterized by freeze quench Mossbauer spectroscopy and its SH parameters become available, then the question arises as to the structure of the unstable species. Mossbauer spectroscopy in itself does not provide enough information to answer this question in a deductive way. However, the more modest question which structures are compatible with the observed Mossbauer parameters can be answered if one is able to reliably predict Mossbauer parameters... 

There may, however, be a number of other reasons to pursue a predictive first principles theory of Mossbauer spectroscopy. For example, one may want to elucidate structure/spectroscopy correlations in the cleanest way. To this end one may construct in the computer a number of models with systematic variations in oxidation states, spin states, coordination numbers, and identity of hgands to name only a few chemical degrees of freedom. In such studies it is immaterial whether these molecules have been made or could be made what matters is that one can find out which structural details the Mossbauer parameters are most sensitive to. This can provide insight into the effects of geometry or covalency that are very difficult to obtain by any other means. 

This chapter presents an overview of first principles theory for diatom-diatom and atom-triatom reactions in comparison with experiments. It is applied to the prototype H2 + OH and H + H2O reactions and their... 

W. Zhong and D. Tomanek, Phys. Rev. Lett., 64, 3054 (1990). First-Principles Theory of... 

Tsukada, M., Kobayashi, K., and Ohnishi, S. (1990). First-principle theory of the scanning tunneling microscopy simulation. J. Vac. Sci. Technol. A 8, 160-165. 

In this author s opinion, the experimental study of gas-surface dynamics has unfortunately dropped off precipitously in the last several years. There are probably many reasons for this funding vagaries, the dominance of the STM in surface science today, the success of first principles dynamics, etc. However, it is absolutely essential to have the most detailed experiments to benchmark first principles theory. Comparisons for even the simple systems considered here demonstrate that theory is far from fully understood. Hopefully, a new generation of experimentalists/theorists will accept this challenge so that the next status report will make this one obsolete. 

Fitzgerald, D. R. and Doren, D. J. Functionalization of diamond(lOO) by cycloaddition of butadiene First-principles theory. Journal of the American Chemical Society 122,12334 (2000). 

The methodological section is intended for readers who are not very familiar with the theoretical details. Accordingly, only part of the formalism is presented in the form of equations however, the general quantum mechanical concepts that allow the computation of NMR observables from first-principles theory, as well as some important technical details, are outlined. Readers who are not interested in methodological details may skip Sects. 2.2 - 2.9, since the subsequent sections do not make excessive references to the methodology part. 

Native defects have sometimes been invoked not just as sources of compensation, but as sources of doping. The nitrogen vacancy in GaN is a prime example for a long time the nitrogen vacancy was thought to be the source of n-type conductivity in GaN. As early as 1983 it was pointed out that unintentional incorporation of oxygen was a more likely explanation [1], Still, it is only recently that unintentional impurities have become widely accepted as the source of n-type conductivity, thanks in part to contributions from first-principles theory (see Datareview A8.1). In this Datareview we will describe some of those theoretical results, for vacancies as well as other native defects (self-interstitials and antisites). Experimental information about native defects in the nitrides is very scarce at this time we will include references where available. 

The usefulness of TDDFT for first-principles theory based computations of chiroptical properties will become obvious after a brief discussion of the basic molecular parameters that describe the response of a molecule to the presence of an electromagnetic (EM) field. Consider, initially, the optical rotation (OR). 

Experimentally, the CD intensity is often quantified by the differential molar absorption coefficient Ae = l — r for the absorption of left-handed vs right-handed circular polarized light, where Ae and e are usually in units of L mol 1 cm-1. The conversion from Ae in L moP1 cm-1 to the molar ellipticity in deg cm2 dmoP1 is [0] = (18,0001n(10)/47r)Ae. The connection with quantities that can be calculated from first-principles theory is given by the following equation [35] ... 

Hemley, R. J., M. D. Jackson, and R. G. Gordon (1985). First principles theory for the equations of state of minerals at high temperature and pressure. Geophys. Res. Lett. 12, 247-50. 

Sdderlind P., Moriarty J. A., and Wills J. M. (1996) First-principles theory of iron up to Earth-core pressures structural, vibrational, and elastic properties. Phys. Rev. B 53, 14063-14072. 

Ge Q, Kose R, King DA (2000) Adsorption energetics and bonding from femtomole calorimetry and from first principles theory. Adv Cat 43 207... 

Karmazyn AD, Fiorin V, JenMns SJ, King DA (2003) First-principles theory and microcalorimetry of CO adsorption on the 211 surfaces of Pt and Ni. Surf Sci 538 171... 

Borthwick D, Fiorin V, Jenkins SJ, King DA Facile dissociation of CO on Fe 211 evidence from microcalorimetry and first-principles theory. Surf Sd (submitted to)... 

Luntz AC, Persson M, Wagner S, Frischkom C, Wolf M (2006) Femtosecond laser induced associative desorption of H from Ru(OOOl) Comparison of first principles theory with experiment. J Chem Phys 124 244702... 

The well-known Landau-Ginsburg-Cochran-Anderson theory is a phenomenological approach. Of the first-principle theories, just one, the vibronic theory of ferroelectricity (e.g., see [1,51]), is consistently based upon electronic structure and chemical nature of the respective compounds. 

Equilibrium statistical mechanics is a first principle theory whose fundamental statements are general and independent of the details associated with individual systems. No such general theory exists for nonequilibrium systems and for this reason we often have to resort to ad hoc descriptions, often of phenomenological nature, as demonstrated by several examples in Chapters 1 and 8. Equilibrium statistical mechanics can however be extended to describe small deviations from equilibrium in a way that preserves its general nature. The result is Linear Response Theory, a statistical mechanical perturbative expansion about equilibrium. In a standard application we start with a system in thermal equilibrium and attempt to quantify its response to an applied (static- or time-dependent) perturbation. The latter is assumed small, allowing us to keep only linear terms in a perturbative expansion. This leads to a linear relationship between this perturbation and the resulting response. 

Wolverton C., First-Principles Theory of 250,000-Atom Coherent Alloy Microstructure, Modelling Simul. Mater. Sci. Eng., in press, (2000). 

The theories of the viscosity of ordinary liquids are mainly scaling relationships there is no first-principles theory for their viscosities. An important scaling relationship is that the viscosity is related to the ratio of the occupied volume to the free volume. The usefulness of variable-pressure studies lies in their ability to probe this directly. Such studies of low-density fluids (gases and supercritical fluids), interpreted through extensions to the kinetic gas theory, have provided a quantitative understanding of their viscosities. How-... 

---