  We present a measurement of two-particle angular correlations in
proton-proton collisions at sqrt(s) = 900 GeV and 7 TeV. The collision events
were collected during 2009 and 2010 with the ATLAS detector at the Large Hadron
Collider using a single-arm minimum bias trigger. Correlations are measured for
charged particles produced in the kinematic range of transverse momentum pT >
100 MeV and pseudorapidity |eta| < 2.5. A complex structure in pseudorapidity
and azimuth is observed at both collision energies. Results are compared to
Pythia 8 and Herwig++ as well as to the AMBT2B, DW and Perugia 2011 tunes of
Pythia 6. The data are not satisfactorily described by any of these models.
