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Ferromagnetic shape memory alloys are modern functional materials capable of undergoing significant reversible strains induced by moderate external magnetic fields due to diffusionless structural transitions and highly mobile twin interfaces. The subject of our work is a theoretical study of the Ni-Mn-Ga alloy, as a representative of the magnetic shape memory alloys, by means of the ab initio simulation methods. It has been shown that the DFT+U method (the Hubbard treatment of the strong on-site Coulomb interaction of localized electrons) used for description of transition metals, can improve quantitative agreement of theoretical and experimental data. The choice of U -parameters for both Mn and Ni atoms was proposed based on the comparison of experimental and theoretical elastic constants of cubic austenite and tetragonal non-modulated martensite. The resulting theoretical results agree with the elasticity measurements. It has been also shown that involving U -correction have strong impact on the predicted formation energies of particular phases.

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Cross-linked polymers have unique and advantageous properties due to the infinite elastic chains. Poly(dimethylsiloxane) (PDMS) belongs into a group of non-toxic, relatively inert and highly elastic polymers (elastomers). In addition, this material is easy to fabricate and has favorable optical and mechanical properties, and it is widely used in fiber optics. Based on testing three different simulation techniques for getting closer insight into the structural background of physical properties of PDMS resin, the molecular dynamics method is chosen. The main topic of this paper is an analysis of relationship between the PDMS cross-linking level and its elasticity. The calculations are performed within the Materials Studio (MS) simulation environment (Biovia Software Inc. USA) using molecular dynamics (MD) theory implemented in MS Forcite Plus module. The obtained results are compared with the newest experimental data available for real PDMS materials.

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