Configuration interaction parallelization

So Hirata, Tensor contraction engine abstraction and automated parallel implementation of configuration-interaction, coupled-cluster, and many-body perturbation theories. J. Phys. Chem. A 107, 4940 (2003). 

This reasoning was found to be paralleled in configuration interaction computations, and a similar triptych was obtained in which surfaces rather than MOs were drawn. Such a triptych has an avoided crossing and bifunnel only on branch A and the reasoning using this variation is parallel to that above. Such computations were used for virtually all of the bicycle-type reactions discussed above. 

An implementation of the configuration-selecting multireference configuration-interaction method on massively parallel architectures 95... 

H. Dachsel, R. Shepard, J. Nieplocha, and R. J. Harrison,/. Comput. Chem., 18,430 (1997). A Massively Parallel Multireference Configuration Interaction Program The Parallel COLUMBUS Program. 

In addition to the SCF calculations which afford molecular orbitals, Cl was also employed. The results of the configuration interaction calculations are given in a parallel triptych in Fig. 15. Here surfaces, or states, are obtained rather than MO s. 

M. Schuler, T. Kovar, H. Lischka, R. Shepard, and R. J. Harrison, Theor. Chim. Acta, 84, 489 (1993). A Parallel Implementation of the COLUMBUS Multireference Configuration Interaction Program. 

G. L. Bendazzoli and S. Evangelisti, ]. Chem. Phys., 98, 3141 (1993). A Vecror and Parallel Full-Configuration-Interaction Algorithm. 

One important conclusion from the full Cl benchmark studies of Bauschlicher, Taylor, Langhoif, and others in the 1980 s is that the MR-CISD method based on CASSCF orbitals provides potential energy surfaces which accurately parallel the full Cl surfaces.14,15 234,238-240 242 254 For example, the CASSCF MR-CISD method predicts singlet-triplet energy separations in CH2 and SiH2 within 0.01 kcal mol-1 and 0.03 kcal mol-1, respectively, of the full Cl results.236,238 The best results are obtained when no threshold is used for reference selection that is, when all CSFs in the CASSCF wavefunction are used as references. This CAS-ref MR-CISD procedure is intimately related107 to second-order configuration interaction (SOCI), which distributes electrons in... 

During the past few years, we have been interested in the calculation and interpretation of transition metal optical spectra conducted in parallel to ongoing experimental studies. To this end, we have developed efficient computer codes to carry out such calculations [45], In particular, a method called spectroscopy oriented configuration interaction (SORCI) was developed [46] and successfully tested in a number of applications [47-57] (for an extensive review on the these developments and their application, see [58]). 

In the case of the Type A rearrangement of 2,5-cyclohexadi-enones, simple one-electron computations of the Mul-liken-Wheland-Mann type were performed that involve iterative modification of resonance integrals. These led to results that were qualitatively similar to triplet configuration interaction computations carried out in parallel. The results are shown in Schemes 1.4a and 1.4b. 

---