My position is *Senior HPC Officer* for supercomputing at the
Department of Physics
at the Technical University of Denmark.

My professional background is in theoretical solid state physics, primarily
electronic structure, total energy and stress calculated within the *Density Functional Theory*.

In the summer of 2002 we built a 2.1 TeraFLOPS Linux cluster supercomputer NIFLHEIM out of 480 desktop PCs, which was one of the fastest computers in Europe at the time of installation. In 2017 NIFLHEIM (after several generations of hardware upgrades) has about 11000 CPU cores and 235 TeraFLOPS peak performance, and continues to provide an important infrastructure for the department's research. See also the Center for Atomic-scale Materials Design (CAMD) homepage.

**Slides of talks:**

*Supercomputernes historie*(PDF-fil 3.5 MB). Foredrag holdt ved HITEK, september 2015.*Stress treated by quantum mechanics*(PDF-file). These are old handwritten transparency slides made by Ole Holm Nielsen, as presented at seminars at Bell Labs and Brookhaven National Lab in June 1983, describing the novel quantum mechanical theorem of the stress tensor.

The original paper is*First-Principles Calculation of Stress*by O. H. Nielsen and Richard M. Martin, Physical Review Letters**50**, 697 (1983).

**Some older scientific papers:**

*Solving large nonlinear generalized eigenvalue problems from Density Functional Theory calculations in parallel*(abstract, compressed PostScript file of the full paper, 73 kB) (June 1999). Published in Applied Numerical Mathematics Vol. 37 (1-2) (2001) pp. 189-199; The paper is available on-line.*Performance Evaluation and Modeling of Reduction Operations on the IBM RS/6000 SP Parallel Computer*(abstract, compressed PostScript file of the full paper, 157 kB). Proceedings of*Workshop on Applied Parallel Computing in Industrial Problems and Optimization*(PARA96), ed. J. Wasniewski, Springer Lecture Notes in Computer Science, vol. 1184, p. 272 (1996).*Data-parallel molecular dynamics with neighbor-lists.*(PostScript file 45 kB). Proceedings of*Workshop on Applied Parallel Computing in Physics, Chemistry and Engineering Science*(PARA95), ed. J. Wasniewski, Springer Lecture Notes in Computer Science, vol. 1041, p. 443 (1995).*Parallel ab-initio molecular dynamics.*(PostScript file 49 kB) (1995)
generation of dislocations. (1995)
*Melting a copper cluster: Critical droplet theory.*(1994)*Stress theorem in the determination of static equilibrium by the density functional method*by P Gomes Dacosta, O H Nielsen and K Kunc, J. Phys. C: Solid State Phys.**19**316 (1986).*Optical phonons and elasticity of diamond at Megabar stresses*by O. H. Nielsen, Physical Review B**34**, 5808-5819 (1986).*Quantum-mechanical theory of stress and force*by O. H. Nielsen and Richard M. Martin, Physical Review B**32**, 3780-3791 (1985).*Stresses in semiconductors: Ab initio calculations on Si, Ge, and GaAs*by O. H. Nielsen and Richard M. Martin, Physical Review B**32**, 3792-3805 (1985).*First-Principles Calculation of Stress*by O. H. Nielsen and Richard M. Martin, Physical Review Letters**50**, 697 (1983).*Lattice dynamics of substitutional 119m-Sn in silicon, germanium, and alpha-tin using an adiabatic bond-charge model*by O. H. Nielsen, Physical Review B**25**, 1225 (1982).

You can send me E-mail at the address Ole.H.Nielsen (at) fysik.dtu.dk.

Check the Center for Atomic-scale Materials Design (CAMD) for more information about our activities.

**Miscellaneous:**

**Address:**

Dr. Ole Holm Nielsen

Department of Physics

Technical University of Denmark

Building 307

DK-2800 Kongens Lyngby

Denmark

**E-mail:**
Ole.H.Nielsen \at/ fysik.dtu.dk

**Telephone:** (+45) 4525 3187.

**Fax:** (+45) 4593 2399.

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