Incommensurate and commensurate antiferromagnetic spin fluctuations in Cr and Cr alloys from ab initio dynamical spin susceptibility calculations

A scheme for making nb initio calculations of the dynamic paramagnetic spin susceptibilities of solids at finite temperatures is described. It is base d on time-dependent density functional theory and employs an electronic mul tiple scattering formalism. Incommensurate and commensurate antiferromagnet ic spin fluctuations in paramagnetic Cr and compositionally disordered Cr95 V5 and Cr95Re5 alloys are studied together with the connection with the nes ting of their Fermi surfaces. We find that the spin fluctuations can be des cribed rather simply in terms of an overdamped oscillator model. Good agree ment with inelastic neutron scattering data is obtained. [S0031-9007(99)089 49-8].