The simplest parametrization of equation of state parameter in the
  scalar field Universe
  In this paper, we have investigated a scalar field cosmological model of
accelerating Universe with the simplest parametrization of equation of state
parameter of the scalar field. We used $H(z)$ data, pantheon compilation of SN
Ia data and BAO data to constrained the model parameters using $\chi^{2}$
minimization technique. We obtain the present values of Hubble constant $H_{0}$
as $66.2^{+1.42}_{-1.34}$, $70.7^{+0.32}_{-0.31}$ and $67.74^{+1.24}_{-1.04}$
for $H(z)$, $H(z)$ + Pantheon and $H(z)$ + BAO respectively. Also, we have
estimated the present age of the Universe in derived model $t_{0} =
14.38^{+0.63}_{-0.64}$ for joint $H(z)$ and pantheon compilation of SN Ia data
which has only $0.88~\sigma$ tension with its empirical value obtained in Plank
collaboration \cite{Ade/2016}. Moreover, the present values of the deceleration
parameter $q_{0}$ come out to be $-0.55^{+0.031}_{-0.038}$,
$-0.61^{+0.030}_{-0.021}$ and $-0.627^{+0.022}_{-0.025}$ by bounding the
Universe in derived model with $H(z)$, $H(z)$ + Pantheon compilation of SN Ia
and $H(z)$ + BAO data sets respectively. We also have performed the
state-finder diagnostics to discover the nature of dark energy.
