Core computation

Savenkov V, Pichler R (2008) Towards practical feasibility of core computation in data exchange. In LPAR. Springer, Heidelberg, pp 62-78... 

Chinese-born US computer engineer An Wang (1920-90) invents the magnetic core computer memory. 

The cyclic voltammetry measurements of both polymers in thin films showed that IIDDT owned HOMO/LUMO level of -5.7/-3.7 eV, and IIDT had HOMO/ LUMO level of -5.8/-3.S eV. Both polymers showed much stronger oxidative peaks than their reductive peaks, and the oxidative peak of IIDDT seems more reversible than that of IIDT (Tig. 2.2c). This result is consistent with the device performance that both the polymers are typical p-type semiconductors and IIDDT exhibited a better performance. Compared with traditional thiophene or fused thiophene based polymers, both polymers showed much deeper HOMO levels, which is attributed to the strong election-withdrawing ability of the isoindigo core. Computational results indicate that the HOMO of the polymers are well delocalized... 

A Colombian system and computer engineer is normally trained in the basic engineering core, computer science, computer systems engineering, software engineering, oigemizationeil informatics, and a few elective courses, which may include Uberal tirts, social science, and humanities content. 

Nowotsch, J., Paulitsch, M. Leveraging multi-core computing architectures in... 

The orbitals from which electrons are removed can be restricted to focus attention on the correlations among certain orbitals. For example, if the excitations from the core electrons are excluded, one computes the total energy that contains no core correlation energy. The number of CSFs included in the Cl calculation can be far in excess of the number considered in typical MCSCF calculations. Cl wavefimctions including 5000 to 50 000 CSFs are routine, and fimctions with one to several billion CSFs are within the realm of practicality [53]. 

Lee Y S, Chae D G, Ree T and Ree F H 1981 Computer simulations of a continuum system of molecules with a hard-core interaction in the grand canonical ensemble J. Chem. Phys. 74 6881-7... 

It has not proved possible to develop general analytical hard-core models for liquid crystals, just as for nonnal liquids. Instead, computer simulations have played an important role in extending our understanding of the phase behaviour of hard particles. Frenkel and Mulder found that a system of hard ellipsoids can fonn a nematic phase for ratios L/D >2.5 (rods) or L/D <0.4 (discs) [73] however, such a system cannot fonn a smectic phase, as can be shown by a scaling... 

Hash codes of molecules which are already pre-computed are suitable for use in fiill structure searches in database applications. The compression of the code of a chemical structure into only one number also makes it possible to compute in advance the transformation results for a whole catalog. The files can be stored and kept complete in the core memory during execution of the program, so that a search can be accomplished within seconds. 

The amount of computation for MP2 is determined by the partial tran si ormatioii of the two-electron integrals, what can be done in a time proportionally to m (m is the u umber of basis functions), which IS comparable to computations involved m one step of(iID (doubly-excitcil eon figuration interaction) calculation. fo save some computer time and space, the core orbitals are frequently omitted from MP calculations. For more details on perturbation theory please see A. S/abo and N. Ostlund, Modem Quantum (. hern-isir > Macmillan, Xew York, 198.5. 

Unlike semiempirical methods that are formulated to completely neglect the core electrons, ah initio methods must represent all the electrons in some manner. However, for heavy atoms it is desirable to reduce the amount of computation necessary. This is done by replacing the core electrons and their basis functions in the wave function by a potential term in the Hamiltonian. These are called core potentials, elfective core potentials (ECP), or relativistic effective core potentials (RECP). Core potentials must be used along with a valence basis set that was created to accompany them. As well as reducing the computation time, core potentials can include the effects of the relativistic mass defect and spin coupling terms that are significant near the nuclei of heavy atoms. This is often the method of choice for heavy atoms, Rb and up. 

---