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1	Nucleation and Growth of SWNTs Studied by QM/MD Simulations Stephan Irle,¹ Guishan Zheng,¹ Zhi Wang,¹ Marcus Elstner,² Keiji Morokuma¹ ¹Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, GA 30322 ²Department of Physics, University of Paderborn, Paderborn, Germany Mechanical Systems Innovation 11th Open Seminar The University of Tokyo, 2005/10/18
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11	DFTB/MD study of high-T carbon chemistry Quantum mechanics is needed to describe the effect of conjugation that controls the chemistry of sp²carbon clusters. MM, even bond-breaking MM, is not appropriate because it does not include the delocalized nature of the quantum world. DFTB calculates the force on the fly during MD (roughly speaking, 10³slower than MM; 10³faster than DFT) Velocity Verlet Integrator (step size: 50 au = 1.2 fs) Isokinetic ensemble: Velocity is universally scaled at averagely every five steps (10% scaling after every ten steps + randomly 10% scaling) (currently) Code is parallelized on EMSL’s MPP2 but scales well only from ~1000 atoms
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