  The first successful theory of superconductivity was the one proposed by
Bardeen, Cooper and Schrieffer in 1957. This breakthrough fostered a remarkable
growth of the field that propitiated progress and questionings, generating
alternative theories to explain specific phenomena. For example, it has been
argued that Bismuth, being a semimetal with a low number of carriers, does not
comply with the basic hypotheses underlying BCS and therefore a different
approach should be considered. Nevertheless, in 2016 based on BCS we put forth
a prediction that Bi at ambient pressure becomes a superconductor at 1.3 mK
[1]. A year later an experimental group corroborated that in fact Bi is a
superconductor with a transition temperature of 0.53 mK [2], a result that
eluded previous work. So, since Bi is superconductive in almost all the
different structures and phases, the question is why Bi-IV has been elusive and
has not been found yet to superconduct? Here we present a study of the
electronic and vibrational properties of Bi-IV and infer its possible
superconductivity using a BCS approach. We predict that if the Bi-IV phase
structure were cooled down to liquid helium temperatures it would also
superconduct at a Tc of 4.25 K.
