Multitrajectory approach

Using equations (28) and (29) we obtain a set of equations for the new expansion coefficients B . The new expansion has better convergence properties than the power series expansion. The functions (x) are harmonic oscillator wave-functions. Thus the hermite expansion involves an expansion around the classical path in a harmonic oscillator basis set. The hermite-corrected GWP can be used in a basis set expansion so as to approach the exact quantum theory fi"om the classical path limit in a systematic fashion. Hence in this sense the method is complementary to the multitrajectory approach discussed below. The advantage of the hermit basis is however that it is an orthorgonal basis and therefore somewhat simpler to work with in practical computations. ... 

Figure 3 A schematic illustration on how the exact quantum limit can be reached through either the multitrajectory approach or a multiconfiguration self-consistent field theory. Correction terms e (t) are introduced to reach the SCF-limit retaining a trajectory concept...

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