  Diamondoids are hydrocarbons having a carbon scaffold comprised from
polymer-like composites of adamantane cages. The present paper describes
computed total energies and "SWB-tension" energies (often referred to as
"strain" energies) for species having $n$ adamantane or diamantane units
sharing pairwise: one carbon atom (spiro-[n]adamantane or
spiro-[$n$]diamantane); one C-C bond (one-bond-sharing-[$n$]adamantane or
one-bond-sharing-[$n$]diamantane); or one chair-shaped hexagon of carbon atoms
(1234-helical-cata-[$n$]diamantanes). Each of the five investigated
polymer-like types is considered either as an acyclic or a cyclic chain of
adamantane- or diamantane-unit cages. With increasing $n$ values, SWB-tension
energies for acyclic aggregates are found to increase linearly, while the net
SWB-tension energies of cyclic aggregates often go thru a minimum at a suitable
value of $n$. In all five cases, a limiting common energy per unit ($E/n$ ) is
found to be approached by both cyclic and acyclic chains as $n\to \infty $, as
revealed from plots of $E/n$ versus $1/n$ for acyclic chains and of $E/n$
versus $1/n^2$ for cyclic chains.
