  First-principles calculations with the full-potential linearized augmented
plane-wave (FP-LAPW) method have been performed to investigate detailed
electronic and linear optical properties of Sr$_{2}$CuO$_{2}$Cl$_{2}$, which is
a classical low-dimensional antiferromagnet (AFM) charge transfer ({\it CT})
insulator. Within the local-spin-density approximation (LSDA) plus the on-site
Coulomb interaction $U$ (LADA+$U$) added on Cu 3d orbitals, our calculated band
gap and spin moments are well consistent with the experimental and other
theoretical values. The energy dispersion relation agrees well with the angle
resolved photoemission measurements. Its linear optical properties are
calculated within the electric-dipole approximation. The absorption spectrum is
found to agree well with the experimental result.
