Hessians momentum

For most molecules, the small momentum expansion of the momentum density requires the full 3x3 Hessian matrix A of n( p) at p = 0. In Cartesian coordinates, this matrix has elements... 

Choosing a coordinate system that diagonalizes the Hessian matrix, the MacLaurin expansion of the three-dimensional momentum density II( p) can be written as [241]... 

Lagrange multiplier General perturbation strength Hessian shift parameter Angular momentum quantum number Lagrange function... 

The conjugate momentum is defined by Pat = —i 9/9 Ar The Hessian matrix is the second derivatives of (R) with respect to the displacement. 

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