In some applications or environments (e.g. fission/fusion reactors, space, sterilization of packaging), radiation effects are highly important and can cause significant damage to, or changed properties of, materials. In other cases, radiation-induced changes of properties are in fact desired. For example, polymers are often irradiated to induce crosslinking for superior qualities. Now, both long-term radiation stability of e.g. reactor materials, and such manufacturing methods can be modeled. However, accurately modeling these radiation processes can be very challenging, because the problem can involve everything from initial defect formation to dislocation dynamics to continuum mechanics.
To quote a review article,
J. Knaster, A. Moeslang & T. Muroga, Materials research for fusion, Nature Physics, vol. 12, 424–434 (2016),
The effects of irradiation on a material’s microstructure and properties are a classic example of an inherently multiscale phenomenon, as schematically illustrated in Fig. 3a. Length scales of relevant processes range from ∼1 Å to structural-component lengths, spanning more than 12 orders of magnitude. In turn, the relevant timescales cover more than 22 orders of magnitude, with the shortest being in the femtosecond range.
They also write (bracketed comment added by me):
Today, a multiscale approach, based on both computational materials science and high-resolution experimental validation, is used to understand the controlling mechanisms and processes of irradiated structural materials. Figure 3b [shown below] illustrates the hierarchical multiscale modelling methodology, which typically combines ab initio
structure calculations on the atomic scale, molecular dynamics
simulations, kinetic Monte Carlo simulations, discrete dislocation dynamics, and rate theory with continuum calculations including thermodynamics and kinetics, as well as phase field calculations. Ab initio methods are required to calculate the most stable defect–cluster configurations, their dissociation energies, or the most likely lattice diffusion paths. Results of ab initio studies can be used as input for molecular dynamics, kinetic Monte Carlo, rate field theory and thermodynamics calculations. Additional links
between different simulation methods are indicated by the arrows
in Fig. 3b.
I think that, in most cases, ab initio methods for these problems means density-functional theory methods. A relevant review article is S.L. Dudarev, Density Functional Theory Models for Radiation Damage, Annual Review of Materials Research, vol. 43, 35-61 (2013).