example, CORRECT.LP supplies detailed statistics describing
several alternative solutions generated by indexing smaller subsets of frames within the previously specified SPOT_RANGE.
This provides insight into which specific set of frames is truly
ideal for SPOT_RANGE.
20. Due to hardware restrictions imposed by the instrument, individual MicroED datasets rarely yield sufficiently high values of
overall completeness to generate tractable direct methods solutions on their own. Merging several datasets can compensate
for this. For n independent datasets, there exist 2
n
-1 unique
ways to exhaustively merge them together. Note that XSCALE
can also truncate each individual dataset at a given resolution
range using INCLUDE_RESOLUTION_RANGE. Only
select individual datasets that generate highly convergent
indexing solutions (i.e., datasets which exhibit strong agreement in parameters such as unit cell dimensions and Laue
symmetry). Forcibly merging inherently discordant datasets
will undeniably prove fruitless.
21. Obtaining an optimal dataset may require systematic screening
of parameters (i.e., adjusting resolution range, re-indexing
individual movies, and merging disparate combinations of
movies) to improve statistics. Attempt to minimize R-factors
and maximize completeness and I/SIGMA. For an example of
the summary statistics produced by XSCALE, see Fig. 4.
22. Many methods exist for generating instruction files for
SHELXD. For example, a custom program (referred to here
as shelxdpro) can facilitate direct methods solutions of protein/peptide structures. To achieve this, shelxdpro prompts
users for information needed to generate instruction files for
running SHELXD or SHELXT. First, shelxdpro prompts the
user to enter the protein sequence, the space group number,
and the unit cell parameters. Shelxdpro uses this information to
calculate Matthews coefficients and suggest feasible choices for
the number of molecules in the asymmetric unit. The user
selects a value, and then shelxdpro calculates the number of
carbons, nitrogens, oxygens, and other atoms required to write
the SFAC, UNIT, FIND, and PLOP statements. Lastly,
shelxdpro asks for the name of the SHELX formatted diffraction data file (.hkl) for this project and an indication of whether
the file contains amplitudes or intensities. Shelxdpro writes this
information, including space group operators in a format that
SHELXD/T accepts. The user can use this instruction file to
run SHELXD/T immediately. The benefit of such a program is
time savings in omitting a search inputs such as space group
operators and number of atoms of each element in the unit cell.
Such a program also relieves the user of remembering the
cryptic lattice code specific to the space group and eliminates
the possibility for formatting errors.
346
Chih-Te Zee et al.
several alternative solutions generated by indexing smaller subsets of frames within the previously specified SPOT_RANGE.
This provides insight into which specific set of frames is truly
ideal for SPOT_RANGE.
20. Due to hardware restrictions imposed by the instrument, individual MicroED datasets rarely yield sufficiently high values of
overall completeness to generate tractable direct methods solutions on their own. Merging several datasets can compensate
for this. For n independent datasets, there exist 2
n
-1 unique
ways to exhaustively merge them together. Note that XSCALE
can also truncate each individual dataset at a given resolution
range using INCLUDE_RESOLUTION_RANGE. Only
select individual datasets that generate highly convergent
indexing solutions (i.e., datasets which exhibit strong agreement in parameters such as unit cell dimensions and Laue
symmetry). Forcibly merging inherently discordant datasets
will undeniably prove fruitless.
21. Obtaining an optimal dataset may require systematic screening
of parameters (i.e., adjusting resolution range, re-indexing
individual movies, and merging disparate combinations of
movies) to improve statistics. Attempt to minimize R-factors
and maximize completeness and I/SIGMA. For an example of
the summary statistics produced by XSCALE, see Fig. 4.
22. Many methods exist for generating instruction files for
SHELXD. For example, a custom program (referred to here
as shelxdpro) can facilitate direct methods solutions of protein/peptide structures. To achieve this, shelxdpro prompts
users for information needed to generate instruction files for
running SHELXD or SHELXT. First, shelxdpro prompts the
user to enter the protein sequence, the space group number,
and the unit cell parameters. Shelxdpro uses this information to
calculate Matthews coefficients and suggest feasible choices for
the number of molecules in the asymmetric unit. The user
selects a value, and then shelxdpro calculates the number of
carbons, nitrogens, oxygens, and other atoms required to write
the SFAC, UNIT, FIND, and PLOP statements. Lastly,
shelxdpro asks for the name of the SHELX formatted diffraction data file (.hkl) for this project and an indication of whether
the file contains amplitudes or intensities. Shelxdpro writes this
information, including space group operators in a format that
SHELXD/T accepts. The user can use this instruction file to
run SHELXD/T immediately. The benefit of such a program is
time savings in omitting a search inputs such as space group
operators and number of atoms of each element in the unit cell.
Such a program also relieves the user of remembering the
cryptic lattice code specific to the space group and eliminates
the possibility for formatting errors.
346
Chih-Te Zee et al.