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are the amount of displacement applied to faces of an originally
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orthogonal box to transform it into the parallelipiped.
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A {prism} region used with the create_box command must have tilt
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factors (xy,xz,yz) that do not skew the box more than half the
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distance of the parallel box length. For example, if xlo = 2 and xhi
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= 12, then the x box length is 10 and the xy tilt factor must be
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By default, a {prism} region used with the create_box command must
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have tilt factors (xy,xz,yz) that do not skew the box more than half
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the distance of the parallel box length. For example, if xlo = 2 and
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xhi = 12, then the x box length is 10 and the xy tilt factor must be
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between -5 and 5. Similarly, both xz and yz must be between
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-(xhi-xlo)/2 and +(yhi-ylo)/2. Note that this is not a limitation,
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since if the maximum tilt factor is 5 (as in this example), then
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configurations with tilt = ..., -15, -5, 5, 15, 25, ... are all
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geometrically equivalent.
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geometrically equivalent. If you wish to define a box with tilt
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factors that exceed these limits, you can use the "box tilt"_box.html
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command, with a setting of {large}; a setting of {small} is the
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See "Section_howto 12"_Section_howto.html#howto_12 of the doc pages
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for a geometric description of triclinic boxes, as defined by LAMMPS,
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and how to transform these parameters to and from other commonly used
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triclinic representations.
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When a prism region is used, the simulation domain must be periodic in
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any dimensions with a non-zero tilt factor, as defined by the
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"boundary"_boundary.html command. I.e. if the xy tilt factor is
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non-zero, then both the x and y dimensions must be periodic.
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Similarly, x and z must be periodic if xz is non-zero and y and z must
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be periodic if yz is non-zero. Also note that if your simulation will
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tilt the box, e.g. via the "fix deform"_fix_deform.html command, the
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simulation box must be defined as triclinic, even if the tilt factors
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When a prism region is used, the simulation domain should normally be
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periodic in the dimension that the tilt is applied to, which is given
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by the second dimension of the tilt factor (e.g. y for xy tilt). This
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is so that pairs of atoms interacting across that boundary will have
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one of them shifted by the tilt factor. Periodicity is set by the
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"boundary"_boundary.html command. For example, if the xy tilt factor
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is non-zero, then the y dimension should be periodic. Similarly, the
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z dimension should be periodic if xz or yz is non-zero. LAMMPS does
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not require this periodicity, but you may lose atoms if this is not
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Also note that if your simulation will tilt the box, e.g. via the "fix
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deform"_fix_deform.html command, the simulation box must be setup to
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be triclinic, even if the tilt factors are initially 0.0. You can
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also change an orthogonal box to a triclinic box or vice versa by
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using the "change box"_change_box.html command with its {ortho} and
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IMPORTANT NOTE: If the system is non-periodic (in a dimension), then
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you should not make the lo/hi box dimensions (as defined in your