![]() Optimizing all other coordinates requires significantly more compute time than fixing all other coordinates. Clicking the Opt All or Fix All button prior to specifying the scan coordinates allows one to perform a "relaxed" scan or "rigid" scan, respectively. Specifying a Coordinate Scan Optimizing or Fixing Other Coordinates During a ScanĬoordinates that are not scanned may be either optimized (O) or fixed (F) at each step. Note that # Steps represents the number of points in addition to the first point, e.g., 10 steps will result in 11 calculations which include both the start and stop value. Specify that Start value, Stop value, and number of Steps for the scanned coordinate. If necessary, re-order and/or re-connect the atoms in the Z-matrix so that the coordinate(s) to be scanned appear in the Z-matrix. Since Z-matrices are not unique, the coordinate to be scanned might not appear in the WebMO-generated Z-matrix. ![]() One can only scan a coordinate (bond length, bond angle, dihedral angle) that appears in the Z-matrix. Since there are more internal coordinates (bond lengths, angles, and dihedrals) than Z-matrix coordinates, one may need to edit the Z-matrix to insure that the relevant coordinates are defined in the Z-matrix. The Z-matrix Editor allows Z-matrix coordinates to be either optimized (O) or fixed (F) during a geometry optimization calculation. However, there may be instances where one desires to hold some coordinates fixed while optimizing the other coordinates, eg, to speed up the calculation, to optimize the geometry in successive stages, or because some aspects are defined by other constraints. Normally all coordinates optimized during a geometry optimization calculation. Then define coordinates in terms of atoms ABOVE them in the Z-matrix.įixing Coordinates During a Geometry Optimization If an atom is added or deleted, a new default Z-matrix is generated, and previous Z-matrix edits are discarded.Ītoms can only reference previously defined atoms in a Z-matrix. Scan details are specified at the bottom of the editor. Use the drop-down box next to each coordinate. Mark coordinates to be optimized (O), fixed (F), or scanned (S, S2) if desired.Note that you can only use previously referenced atoms in your definition. The lengths, angles, and dihedrals will be re-calculated. Change the number(s) in the appropriate column. ![]()
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