晶体结构2.pdf

: .
MIT OpenCourseWare
Read: Sheldrick, G. M. Acta Cryst. Sect. A
(1990), 46, 467. Direct methods have problems in the
presence of inversion centers (use PATT or solve in non-
centrosymmetric space group and transform by hand).
Sometimes TREF 1000 (or 5000) helps.
Structure Solution with SHELXS
TITL b11 in P2(1)/c
CELL
ZERR
LATT 1
SYMM -X, +Y, -Z
SFAC C H N SI CL
UNIT 96 140 4 4 8
TREF
HKLF 4
END
TITL b11 in P2(1)/c
CELL
ZERR
LATT 1
SYMM -X, +Y, -Z
SFAC C H N SI CL
UNIT 96 140 4 4 8
PATT
HKLF 4
END
2Structure Solution with SHELXS
TITL b11 in P2(1)/c
CELL
ZERR
LATT 1
SYMM -X, +Y, -Z
SFAC C H N SI CL
UNIT 96 140 4 4 8
TREF 1000
HKLF 4
END
Force 1000 cycles of direct methods. More than 5000 is not
really sensible.
In stubborn cases try ESEL or possibly TEXP (see manual) or,
much easier, use SHELXD (XM) instead.
Structure Solution with SHELXS
TITL b11 in P2(1)/c
CELL
ZERR
LATT 1
SYMM -X, +Y, -Z
SFAC C H N SI CL
UNIT 96 140 4 4 8
TREF -363117
HKLF 4
END
TREF followed by a negative number generates only the
solution with the given code number (to be found in the .lst file
from the SHELXS run before!).
Sometimes it is possible to solve the structure in a space
group of lower symmetry (P1 instead of P