When OVERLAP is highlighted (the default) then crystal fragments are allowed to overlap, ie. have atoms in common.
When OVERLAP is not highlighted then crystal fragments are required to be separate from each other, ie. have no atoms in common.
Remarks
In most situations the OVERLAP and EXHAUSTIVE commands are both highlighted. This setting results in the following "home" prompt in the dialogue area:
Search for ALL crystal fragments OVERLAP of crystal fragments permitted Select a menu command or TO-BUILD to return to the BUILD menu.
OVERLAP of crystal fragments forbidden
Ex.1 Suppose we conduct a survey of the four torsion angles of the 4-membered carbocyclic ring.
If the search is conducted with EXHAUSTIVE and OVERLAP both highlighted then all occurrences of the 4-ring crystal fragment should be located, including those which have atoms in common
(ie. OVERLAP is permitted). The fragments located are:
BHPNPH C51 C61 C71 C11 C52 C62 C72 C12
BHPNPH C2/c Z = 16 Z' = 2
BILSUK C7 C5 C6 C1 C7' C5' C6' C1'
BILSUK P21/c Z = 4 two half-molecules per asymmetric unit
BIRGEO C1 C6 C10 C5 C1 C6 C7 C2 C2 C7 C8 C3 C5 C10 C9 C4 C3 C4 C9 C8
BIRGEO P21/c Z = 4 Z' = 1
BORVOT C1 C10 C11 C12 C15 C24 C25 C26 C2 C5 C4 C3 C16 C19 C18 C17 C9 C6 C7 C8 C23 C20 C21 C22
BORVOT Pbca Z = 16 Z' = 2
Ex.2 Suppose we conduct a survey of the four torsion angles of the 4-membered carbocyclic ring.
If the search is conducted with EXHAUSTIVE highlighted but OVERLAP not highlighted then all occurrences of the 4-ring crystal fragment should be located, excluding those which have atoms in common (ie. OVERLAP is not permitted). The fragments located are:
BHPNPH C51 C61 C71 C11 C52 C62 C72 C12
BHPNPH C2/c Z = 16 Z' = 2
BILSUK C7 C5 C6 C1 C7' C5' C6' C1'
BILSUK P21/c Z = 4 two half-molecules per asymmetric unit
BIRGEO C1 C6 C10 C5 C2 C7 C8 C3
BIRGEO P21/c Z = 4 Z' = 1
BORVOT C1 C10 C11 C12 C15 C24 C25 C26 C2 C5 C4 C3 C16 C19 C18 C17 C9 C6 C7 C8 C23 C20 C21 C22
BORVOT Pbca Z = 16 Z' = 2
Ex.3 Suppose we conduct a survey of the four torsion angles of the 4-membered carbocyclic ring.
If the search is conducted with EXHAUSTIVE not highlighted and OVERLAP not highlighted then only one occurrence of the 4-ring crystal fragment should be located in each entry. The fragments located are:
BHPNPH C51 C61 C71 C11
BHPNPH C2/c Z = 16 Z' = 2
BILSUK C7 C5 C6 C1
BILSUK P21/c Z = 4 two half-molecules per asymmetric unit
BIRGEO C1 C6 C10 C5
BIRGEO P21/c Z = 4 Z' = 1
BORVOT C1 C10 C11 C12
BORVOT Pbca Z = 16 Z' = 2