  In this paper, we have studied electron correlation and Gaunt interaction
effects in ionization potentials (IPs) and hyperfine constants A of
2p$^2P_{1/2}$ and 2p$^2P_{3/2}$ states along with the fine structure splitting
(FSS) between them for boron isoelectronic sequence using relativistic
coupled-cluster (RCC) method. The range of atomic number Z has been taken from
8 to 21. Gaunt contributions are presented at both Dirac-Fock (DF) and
coupled-cluster (CC) levels of calculations. The Gaunt corrected correlated
results of the IPs and the FSS are compared with the results of NIST. Important
correlation contributions like core correlation, core polarisation, pair
correlation etc. are studied for hyperfine constants A. Many distinct features
of correlation and relativistic effects are observed in these studies. With
best of our knowledge, within Gaunt limit, most of the hyperfine constants are
presented for the first time in the literature.
