Geometry Optimisation with CASTEP

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We can see that the result is an initial vertical relaxation followed by asymmetric dimerisation of the top layer silicon atoms. Asymmetric dimerisation has been seen experimentally [6] and has been confirmed by detailed theoretical calculations [7]. The bond lengths are shown in figure 11 below (the numbers in brackets are taken from reference [7]). Figure 11:Principle bond lengths compared with the results of other theoretical work (in brackets).
It is interesting to look at the evolution of the total energy and the forces as the calculation progresses. Figures 12 and 13 below shows this. Figure 12:The variation of the total energy with BFGS iteration number. Figure 13:The variation of the maximum force with BFGS iteration number.
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 and 20: Next: External pressure that is Up:
Page 21 and 22: Next: General Job Parameters Up: In
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: thickness We can see that the total
Page 55 and 56: Next: About this document ... Up: G

Geometry Optimisation with CASTEP

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