[en] The response of the atomic nucleus to gamma radiation provides crucial information about its structure and the forces acting between constituent nucleons. To access these excited modes, within the framework of superfluid nuclear density functional theory, the linear response is one of the commonly used methods. Traditionally, the linear response, or the quasiparticle random phase approximation (QRPA), has been formulated in the matrix form. However, the matrix QRPA becomes computationally very demanding with deformed nuclei, resulting usually truncations in the used model space. To circumvent the large CPU and memory cost of the matrix QRPA, the finite amplitude method (FAM) solves the QRPA problem iteratively. We have recently developed a FAM-QRPA module which allows to handle non-axial multipole modes, without any truncations. This work demonstrated the first practical application of the iterative QRPA method for deformed superfluid nuclei, with an arbitrary multipole transition operator. As an application of the FAM-QRPA, we have done a systematic computation of the nuclear photo absorption cross sections for the heavy rare-earth nuclei. The computed results show that for isotopes heavier than erbium, there is some deficiency in the cross section, when compared to experimental data. A simple modification of the Thomas-Reiche-Kuhn sum rule enhancement factor cannot cure this deficiency. This document is composed of an abstract and the slides of the presentation. (author)