  Nuclear structure of 7Be, 8B and 7,8Li is studied within the ab initio
no-core shell model (NCSM). Starting from the high-precision CD-Bonn 2000
nucleon-nucleon (NN) interaction, wave functions of 7Be and 8B bound states are
obtained in basis spaces up to 10 hbar Omega and used to calculate channel
cluster form factors (overlap integrals) of the 8B ground state with 7Be+p. Due
to the use of the harmonic oscillator (HO) basis, the overlap integrals have
incorrect asymptotic properties. We fix this problem in two alternative ways.
First, by a Woods-Saxon (WS) potential solution fit to the interior of the NCSM
overlap integrals. Second, by a direct matching with the Whittaker function.
The corrected overlap integrals are then used for the 7Be(p,gamma)8B S-factor
calculation. We study the convergence of the S-factor with respect to the NCSM
HO frequency and the model space size. Our S-factor results are in agreement
with recent direct measurement data.
