First results are presented of the simulation of the thermodynamic properties of intrinsic point defects and interstitial oxygen in single crystal germanium. The results are based on molecular dynamics calculations using a Stillinger-Weber potential and on the Einstein equation. Two different molecular dynamics codes are used and compared. A novel molecular dynamics algorithm was implemented, which allows describing the migration path of interstitial oxygen without assumptions on saddle point and positions of neighbouring atoms. (c) 2005 Elsevier B.V. All rights reserved.