Single-reference techniques, transition

There are many computational investigations of transition metal oxides, see, e.g., the recent review by Harrison [7]. Some studies have included the whole sequence of 3d metal oxides. In one of these studies, Bauschlicher and Maitre [17], employed different high-level ab initio methods. It was found that ScO - MnO and CuO were well described by single-reference based techniques and that the CCSD(T) method gave spectroscopic constants (re, uje and D0) in good agreement with experiments. For FeO - NiO multi-reference based techniques (CASSCF/ICACPF) were necessary to get good results. 

MCSCF) wave function, which determines a set of MOs. The remaining electron correlation effects are accounted for by MRCI, MRCC, or MRPT techniques, where MR stands for multireference. They have a more ample range of applicability (ground state, excited states, transition states) than single-reference methods... 

Most of the DNA in nature has the double helical secondary structure. The hydrogen bonds between the base pairs provide the stability of the double helix. Under certain conditions the hydrogen bonds are broken. During the replication process itself, this happens and parts of the double helix unfold. Under other conditions, the whole molecule unfolds, becomes single stranded, and assumes a random coil conformation. This can happen in denaturation processes aided by heat, extreme acidic or basic conditions, etc. Such a transformation is often referred to as helix-to-coil transition. There are a number of techniques that can monitor such a transition. One of the most sensitive is the measurement of viscosity of DNA solutions. 

Abstract. We report progress towards making a precise measurement of the 2S Lamb shift in singly-ionised helium by spectroscopy of the 2S-3S transition. The motivation for the experiment is discussed with reference to recent developments in the theory of quantum electrodynamics (QED) and a description of the apparatus and techniques used is given. 

The experiments discussed in this book are diverse, but they break down into two broad categories (1) resonant infrared methods in which ultrafast IR pulses are tuned to the wavelength of the vibrational transition and (2) Raman methods (in some instances referred to as impulsive stimulated scattering), in which two visible wavelengths have a difference in frequency equal to the vibrational frequency. In some experiments, infrared and Raman techniques are combined in a single measurement. 

The dynamic window of a given NMR technique is in many cases rather narrow, but combining several techniques allows one to almost completely cover the glass transition time scale. Figure 6 shows time windows of the major NMR techniques, as applied to the study of molecular reorientation dynamics, in the most often utilized case of the 2H nucleus. Two important reference frequencies exist The Larmor frequency determines the sensitivity of spin-lattice relaxation experiments, while the coupling constant 8q determines the time window of line-shape experiments. 2H NMR, as well as 31P and 13C NMR, in most cases determines single-particle reorientational dynamics. This is an important difference from DS and LS, which access collective molecular properties. 

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