Diebenkorn in New Mexico (Phillips Collection, 1600 21st St. NW, Washington, D.C., up through Sunday). If you haven’t yet seen this important show of abstract paintings and works on paper, don’t delay–it closes this weekend. Richard Diebenkorn created these works when he lived in Albuquerque from 1950 to 1952, and the best of them suggest with uncanny exactitude the austere yet wrenchingly vivid New Mexico landscape (TT).