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* aflow - STEFANO CURTAROLO Duke University 2003-2017 *
* High-Throughput ab-initio Computing Project *
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AFLOW/ANRL Prototypes
AFLOW implementation: Stefano Curtarolo and David Hicks
Citation Information: M. J. Mehl, D. Hicks, C. Toher, O. Levy, R. M. Hanson, G. L. W. Hart, and S. Curtarolo,
The AFLOW Library of Crystallographic Prototypes, Comp. Mat. Sci. (2016). (under review)
The AFLOW/ANRL Library consists of 288 crystallographic prototypes from the above paper. These
prototypes have been programmed into AFLOW. The list of prototypes and how to call them can be
found in aflow_anrl.cpp. The prototypes are generally listed in the order they appear in the
paper (low space group number to high space group number).
Note: This implementation of the geometric prototypes allows for the creation of different
structure prototypes depending on the parameters chosen. Therefore, these prototypes are quite
general and powerful.
The general format for the command is as follows:
aflow --proto=label --params=a,b/a,c/a,alpha,beta,gamma,x1,y1,z1,x2,y2,z2,... [--hex]
Example:
aflow --proto=ABC4_oP12_16_ag_cd_2u --params=5.61,1.01069518717,1.61319073084,0.2,0.26,0.125,0.74,0.8,0.63
A description of each input is described below:
label: The label is a string that provides a great deal of information regarding the
geometric prototype. The information is separated by underscores into different
fields.
- Field 1: Stoichiometry
- Field 2: Pearson symbol
- Field 3: Space group number
- Field 4: Wyckoff letters (in alphabetic order) associated with species A
- Field 5: Wyckoff letters (in alphabetic order) associated with species B
- Field 6: Wyckoff letters (in alphabetic order) associated with species C
- ...
- ...
- ...
parameters: The parameters are necessary to create the structure prototype.
The parameter information is separated by commas. The parameters are
type double, which specify the degrees of freedom in the prototype.
- a,b/a,c/a : Magnitudes of lattice vectors. Note, there may not be a need
to specify all magnitudes, since higher symmetry prototypes
have lattice vector restrictions:
TRI/MCL/MCLC/ORC/ORCC/ORCF/ORCI: a,b/a,c/a
TET/BCT/HEX/RHL: a,c/a
CUB/FCC/BCC: a
- alpha,beta,gamma : Angles between lattice vectors. Note, there may not be a need
to specify all angles, since higher symmetry prototypes
have lattice vector restrictions:
TRI: alpha,beta,gamma
MCL/MCLC: beta
Rest: None
- x1,y1,z1,x2,... : Coordinates of Wyckoff positions, which have a degree of
variability. Caution: Order these parameters with care.
The order of the Wyckoff positions is found in the paper.
[--hex]: For rhombohedral systems, there are two choices for representing the protoypes:
rhombohedral (RHL) or hexagonal (HEX).
- RHL cell: a=b=c and alpha=beta=gamma (better for ab-initio, smaller than HEX)
- HEX cell: a=b and gamma=120 (this cell is 3 times larger than the RHL)
The default representation is RHL. To show the prototype in the HEX representation,
we add the --hex flag.
NOTE: Only applicable for rhombohedral systems.
For additional information contact: David Hicks (d.hicks@duke.edu)
AFLOW/ANRL Prototypes
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