  We investigate the early (t < 1 day) kilonova from the neutron star merger by
deriving atomic opacities for all the elements from La to Ra (Z = 57 - 88)
ionized to the states V - XI. The opacities at high temperatures for the
elements with open f-shells (e.g., lanthanides) are exceptionally high,
reaching kappa_{exp} ~ 10^4 cm2/g at lambda < 1000 A at T ~ 70,000 K, whereas,
the opacities at the same temperature and wavelengths for the elements with the
open d-, p-, and s-shells reach kappa_{exp} ~ 1 cm2/g, 0.1 cm2/g, and 0.01
cm2/g, respectively. Using the new opacity dataset, we derive the early
kilonovae for various compositions and density structures expected for neutron
star merger ejecta. The bolometric luminosity for the lanthanide-rich ejecta
shows distinct signatures and is fainter than that for the lanthanide-free
ejecta. The early luminosity is suppressed by the presence of a thin outer
layer, agreeing with the results of Kasen et al. (2017) and Banerjee et al.
(2020). The early brightness in Swift UVOT filters and in the optical g-, r-,
i-, z-filters for a source at 100 Mpc are ~ 22 - 20 mag and ~ 21 - 19 mag,
respectively, at t ~ 0.1 days. Such kilonovae are ideal targets for the
upcoming UV satellites, such as ULTRASAT, UVEX, and DORADO, and the upcoming
surveys, e.g., Vera Rubin Observatory. We suggest the gray opacities to
reproduce the bolometric light curves with and without lanthanides are ~ 1 - 20
cm2/g and ~ 0.8 - 1 cm2/g.
