231 eng reportzib 0 1996-06-19 1996-06-19 -- The Car-Parrinello (CP) approach to ab initio molecular dynamics serves as an approximation to time-dependent Born-Oppenheimer (BO) calculations. It replaces the explicit minimization of the energy functional by a fictitious Newtonian dynamics and therefore introduces an artificial mass parameter $\mu$ which controls the electronic motion. A recent theoretical investigation shows that the CP-error, i.e., the deviation of the CP--solution from the BO-solution {\em decreases} like $\mu^{1/2}$ asymptotically. Since the computational effort {\em increases} like $\mu^{-1/2}$, the choice of $\mu$ has to find a compromise between efficiency and accuracy. The asymptotical result is used in this paper to construct an easily implemented algorithm which automatically controls $\mu$: the parameter $\mu$ is repeatedly adapted during the simulation by choosing $\mu$ as large as possible while pushing an error measure below a user-given tolerance. The performance and reliability of the algorithm is illustrated by a typical example. SC-96-20 231 urn:nbn:de:0297-zib-2311 Appeared under the title: "An adaptive accuracy control of Car-Parrinello simulations" in: Numer. Math. 83 (2) 179-186 (1999) Folkmar A. Bornemann Christof Schütte SC-96-20 Informatik, Informationswissenschaft, allgemeine Werke ZIB Allgemein Schütte, Christof https://opus4.kobv.de/opus4-zib/files/231/SC-96-20.ps https://opus4.kobv.de/opus4-zib/files/231/SC-96-20.pdf