COLUMBUS Program System

COLUMBUS Program System Dr. Isaiah Shavitt Dr. Russell M. Pitzer Department of Chemistry Ohio State University Columbus, OH 43210, U.S.A. 

Analytic Evaluation of Nonadiabatic Coupling Terms and Efficient Searching Algorithm of Conical Intersections within the COLUMBUS Program System Szalay V. 

H + CH2 CH3 This reaction has been the subject of several experimental [11] and theoretical studies [12]. The published theoretical work calculated portions of the hindered rotation barriers for different values of Rh-C Ihe distance of the attacking H from CH2. This calculation employed a tzp basis set [13] with an multireference singles and doubles configuration interaction (MRSDCI) wavefunction and was carried out with the COLUMBUS program system [14]. This work has now been supplemented by a much more extensive mapping of the hindered rotational potential with a less expensive dzp basis set [13], Tests show that Vtr is not sensitive to dzp or tzp basis set selection. 

Electronic structure calculations have been carried out for F approaching CH3 frozen in its equilibrium configuration. Only three directions of approach were examined (1) along the CH3 C3V axis, (2) in the 4 atom plane approaching the H end of a C2v C-H bond of CH3, and (3) as previous but approaching the C end of a C2v C-H bond. As in the H+CH2 study, a dzp basis set [13] was employed in an MRSDCI calculation with the COLUMBUS program system [14]. All three surfaces were characterized along each of the three directions of approach. 

A parallel implementation of the COLUMBUS MRSDCl program system described by Schuler et al.24 uses a coarse-grained parallelization approach... 

H. Lischka, R. Shepard, R. M. Pitzer, I. Shavitt, M. DaUos, T. Miiller, P. G. Szalay, M. Seth, G. S. Kedziora, S. Yabushita, and Z. 21iang, High-Level Multireference Methods in the Quantum-Chemistry Program System COLUMBUS Analytic MR-CISD and MR-A(JCC Gradients and MR-A(3CC-LRT for Excited States, GUGA Spin-Orbit Cl and Parallel Cl Density, Phys. Chem. Chem. Phys. 3, 664-673 (2001). 

Lischka H, Muller T, Szalay PG, Shavitt I, Pitzer RM, Shepard R (2011) COLUMBUS—a program system for advanced multireference theory calculations. In Wiley Interdisciplinary Reviews Computational Molecular Science, vol 1, p 191... 

High-level multireference methods in the quantum-chemistry program system COLUMBUS analytic MR-CISD and MR-AQCC gradients and MR-AQCC-LRT for excited states, GUGA spin-orbit Cl and parallel Cl density. Phys Chem Chem Phys 3(5) 664-673... 

Shepard R, Shavitt I, Pitzer RM, Comeau DC, Pepper M, Lischka H, Szalay PG, Ahlrichs R, Brown FB, Zhao JG (1988) A progress report on the status of the columbus MRCI program system. Int J Quan Chem 149-165... 

Lischka, H., Shepard, R., Pitzer, R. M., Shavitt, L, Dallos, M., Muller, T., Szalay, P. G., Seth, M., Kedziora, G. S., Yabushita, S., Zhang, Z. Y. (2001). High-level multireference methods in the quantum-chemistry program system COLUMBUS Analytic MR-CISD and MR-AQCC gradients and MR-AQCC-LRT for excited states, GUGA spin-orbit Cl and parallel Cl density. Physical Chemistry Chemical Physics, 3(5), 664-673. 

Stone H (2005) Economic analysis of stationary PEMPC systems DOE hydrogen program FY 2005 progress report 961. Battelle Memorial Institute, Columbus, OH... 

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