  Background: To access selected excited states of nuclei, within the framework
of nuclear density functional theory, the quasiparticle random phase
approximation (QRPA) is commonly used. Purpose: We present a computationally
efficient, fully self-consistent framework to compute the QRPA transition
strength function of an arbitrary multipole operator in axially-deformed
superfluid nuclei. Methods: The method is based on the finite amplitude method
(FAM) QRPA, allowing fast iterative solution of QRPA equations. A numerical
implementation of the FAM-QRPA solver module has been carried out for deformed
nuclei. Results: The practical feasibility of the deformed FAM module has been
demonstrated. In particular, we calculate the quadrupole and octupole strength
in a heavy deformed nucleus $^{240}$Pu, without any truncations in the
quasiparticle space. To demonstrate the capability to calculate individual QRPA
modes, we also compute low-lying negative-parity collective states in
$^{154}$Sm. Conclusions: The new FAM implementation enables calculations of the
QRPA strength function throughout the nuclear landscape. This will facilitate
global surveys of multipole modes and beta decays, and will open new avenues
for constraining the nuclear energy density functional.
