Geometry optimization

The geometry can be optimized by adding the GeoOpt key block. Within the block you can specify the maximum number of cycles and the convergence criterion. The optimizer works with Cartesian coordinates and a Quasi Newton stepper. The initial Hessian is by default the unit matrix, but can also be loaded from a previous geometry optimization or frequency run. Various constraints are possible such as bond distances and angles. The GDIIS convergence accelerator is available but is disabled by default. A geometry optimization can be restarted from a previous result (.runkf) file. The geometry can be optimized in the non-relativistic and scalar relativistic ZORA case.