Geometry Optimisation with CASTEP

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Next: The .param file Up: The .cell file and Previous: The location of the External pressure that is to be applied to the supercell A pressure tensor is used to specify any external pressure that is to be applied to the cell %BLOCK EXTERNAL_PRESSURE units %ENDBLOCK EXTERNAL_PRESSURE Here we have, for example - the -component of the pressure and the -component of the pressure and so on. The default units are GPa. If the whole BLOCK is omitted then no external pressure is applied by default. For example we might specify %BLOCK EXTERNAL_PRESSURE atm 1 0 0 1 0 1 %ENDBLOCK EXTERNAL_PRESSURE Which will apply a hydrostatic pressure of 1 atmosphere upon the supercell from all three directions 2005-04-04
Next: General Job Parameters Up: Inputs Previous: External pressure that is The .param file This contains all of the parameters which the user requires within the calculation. The parameters can be specified in any order but only one parameter must be specified per line. The most fundamental parameter is the task (there are other types of CASTEP calculation besides geometry optimisation). A geometry optimisation .param file should always include the line task : GeometryOptimization Note the format keyword : value Most of the parameters (there are very many of them) can be left as defaults. The main parameters that the user may find useful to specify and why are outlined below Subsections ● ● ● ● General Job Parameters Basis Set Parameters Variable Cell Calculations Electronic Minimisation Parameters 2005-04-04
Page 1 and 2: Next: Recipe Geometry Optimisation
Page 3 and 4: Next: Inputs Up: Geometry Optimisat
Page 5 and 6: Next: The Size and Shape Up: Inputs
Page 7 and 8: In both cases if [units] are not sp
Page 9 and 10: After the atomic symbol or the atom
Page 11 and 12: KPOINTS_MP_SPACING [units] Where is
Page 13 and 14: 2005-04-04
Page 15 and 16: Next: Atomic masses Up: The .cell f
Page 17 and 18: It is possible to fix the positions
Page 19: Next: External pressure that is Up:
Page 23 and 24: When a calculation that was stopped
Page 25 and 26: Next: Electronic Minimisation Param
Page 27 and 28: Next: Example - Bulk Silicon Up: Th
Page 29 and 30: the default value is 3 but it must
Page 31 and 32: We must now choose a supercell to e
Page 33 and 34: Next: The .castep file Up: Geometry
Page 35 and 36: 4 -2.14844155E+002 -9.84322032E-003
Page 37 and 38: BFGS: Final Configuration: ========
Page 39 and 40: Next: Other output files Up: Output
Page 41 and 42: Next: A Variable Cell calculation U
Page 43 and 44: arbitrary set of basis set paramete
Page 45 and 46: 3 -2.16474423E+002 2.10512829E-007
Page 47 and 48: Figure 6:A finite vacuum gap may ca
Page 49 and 50: 0.0000000000 0.0000000000 24.503725
Page 51 and 52: thickness We can see that the total
Page 53 and 54: It is interesting to look at the ev
Page 55 and 56: Next: About this document ... Up: G

Geometry Optimisation with CASTEP

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