3.49. PREABS: Interactive crystal shape manipulation
| diff [a] | diffractometer description |
| orient[a] | crystal orientation |
| orface [b] | microscope orientation |
| facept[b] | face described by three points |
| face[b] | face described by  ,  , and distance |
| faceom[b] | face described by ,,  and distance |
| faceml[b] | face described by Miller indices and distance |
| Notes: a. diff and orient are mandatory. b. Only one of the methods orface-facept, face or faceml may be used to specify the faces of the crystal. | |
| PREABS | Option | Code | Arg | Def | |
| double buffered graphics [a] | dbuf | ||||
| precision scale factor [b] | pscal | q | scale distance | ||
| Notes: a. On some screens and for large window sizes, coppying the back buffer to the visible window adds a significant time lag which detracts from general performance. On other displays, particularly linux PCs this option can help quite a bit. b. This option is used to avoid rounding errors for small crystals. | |||||
| diff [a] | 1 | sense of rotation of the2 circle | c | clockwise | |
| a | anti-clockwise | ||||
| 2 | sense of rotation of the circle | c | clockwise | ||
| a | anti-clockwise | ||||
| 3 | sense of rotation of the circle | c | clockwise | ||
| a | anti-clockwise | ||||
| 4 | sense of rotation of the circle | c | clockwise | ||
| a | anti-clockwise | ||||
| 5 | sense of rotation of the  circle | c | clockwise | ||
| a | anti-clockwise | ||||
| 6 | value of at = 90 degrees | 0 | |||
| 7 | minimum possible (-180 < < 180) | -48 | |||
| 8 | maximum possible (-180 < < 180) | 58 | |||
| Notes: a. See the Diffractometer Description in the ABSORB for the method to be used in determining the sense of rotation for each diffractometer circle. | |||||
| orient | 1-3 | hkl indices of first orienting reflection | |
| 4 | angle of first orienting reflection
[a] | ||
| 5 | angle of first orienting reflection | ||
| 6-8 | hkl indices of second orienting reflection | ||
| 9 | angle of second orienting reflection | ||
| 10 | angle of second orienting reflection | ||
| Notes: a. Angles in the bisecting mode. (For CAD see Ch. II of the CAD User's Manual.) | |||
| orface [a] | 1-3 | x, y, z coordinates of first point on orienting face | |
| 4-6 | x, y, z coordinates of second point on orienting face | ||
| 7-9 | x, y, z coordinates of third point on orienting face | ||
| Notes: a. If the orface-facept method is used for entering face data, two orface lines must be used. The first contains the coordinates of three points on a plane parallel to the first orienting reflection given on the orient line. The second orface line contains the coordinates of three points on a plane parallel to the second orienting reflection given on the orient line. | |||
| facept | 1-3 | x, y, z coordinates of first point on bounding face | |
| 4-6 | x, y, z coordinates of second point on bounding face | ||
| 7-9 | x, y, z coordinates of third point on bounding face |
| face | 1 | for bounding face (angles in the bisecting mode) | |
| 2 | for bounding face | ||
| 3 | distance to origin from bounding face in mm |