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The tooltips modeled in this work are intended to be used only in carefully controlled environments ( e. g., vacuum ).
Maximum acceptable limits for tooltip translational and rotational misplacement errors are reported in Peng et al.
( 2006 ) -- tooltips must be positioned with great accuracy to avoid bonding the dimer incorrectly.
Peng et al.
( 2006 ) reports that increasing the handle thickness from 4 support planes of C atoms above the tooltip to 5 planes decreases the resonance frequency of the entire structure from 2. 0 THz to 1. 8 THz.
More importantly, the vibrational footprints of a DCB6Ge tooltip mounted on a 384-atom handle and of the same tooltip mounted on a similarly constrained but much larger 636-atom " crossbar " handle are virtually identical in the non-crossbar directions.
Additional computational studies modeling still bigger handle structures are welcome, but the ability to precisely position SPM tips to the requisite atomic accuracy has been repeatedly demonstrated experimentally at low temperature, or even at room temperature constituting a basic existence proof for this capability.

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