Example 3

CRISP can be used with PIG to interactively solve structures

CRISP uses random-phase invariant methods to provide initial structural models from phased Fourier E-maps, and then iterative application of diagonal least-squares refinement, peak-list elimination and molecular geometry constraints to progressively refine the final models. These are automatically displayed using PIG, as shown below.

Shown here is the window of PIG (Portable Interactive molecular Graphics) which has the following features:

  • click and drag molecular rotation, zoom and translation,
  • animation-spin mode
  • double buffered graphics mode,
  • red-green stereo view,
  • 3 modes of label sorting, (for atom list editing)
  • automatic Uiso values for new built H atoms,
  • on-screen control over ORTEP generation,
  • enhanced fragment mode for specifying ORTEP plot sites
  • scrollable PEKPIK peak height viewing threshold.