ABSTRACT
The elongation finite-field method is applied to the evaluation of the nonlinear susceptibilities of 3-Methyl-4-nitropyridine 1-oxide (POM) crystal. Static (hyper)polarizabilities of one-dimensional POM clusters, built along each of three crystal axes, are obtained by the elongation-FF method for the clusters containing up to 15 POM unit cells. It is found that the crystal packing effects along the b axis are the most prominent. For the first hyperpolarizability tensor component β abc , packing along the b axis has an increase by about 8% whereas packing along the a and c axis shows a decrease by 2 and 23%, respectively. For the second hyperpolarizabilities the crystal packing effects are much stronger than for the polarizability and first hyperpolarizability. The dominant γ bbbb component displays a large increase (by 120%) when packing along the b axis or a decrease (by 64%) when packing along the c axis.
