摘要
When M is compact, a 2-harmonic map f:M→N between Riemannian mani-folds is a critical map of 2-energy functional E2（f）=∫M‖（f）‖2*1. Its tension field（?）（f） is exactly the Jacobi field. When the target manifold N is a unit sphere Sm+P（m=dimM, p=codlin M）, using the method of moving frames, we have studied the 2-harmonic isometric immersion f:M→Sm+p, and obtained the following results, in which ‖B（f）‖2 denotes the square norm of the second
