“Nanoscale physics”
Theoretical modeling of laser-stimulated nanostructures
L.V. Shmeleva, A.D. Suprun, S.M. Yezhov, V.V. Datsyuk
Department of Theoretical Physics, Faculty of Physics, Taras Shevchenko National University of Kyiv. Volodymyrska Street, 64/13, Kyiv-01601, Ukraine. 
E-mail: lshmel@univ.kiev.ua

Analytical-numerical simulation of surface destruction by laser pulse is based on solving an inhomogeneous system of equations of continuum mechanics. The boundary conditions are determined on the boundary between the two phases (the condensed medium and the gas phase) by means of projecting bulk equations to this boundary. This method of determining all boundary conditions leads to the fact that they are formulated in the local coordinate system. It is beginning is located at the point of the surface at the interface between the condensed medium and the gas phase in the impulse action region. When the solid surface does not collapse, the coordinate system will remain motionless relative to the observer. But when the destruction occurs, then the local system is rigidly bound to the surface of the solid medium. Such systems describe events directly at each individual point on the surface. This complicates the theoretical interpretation of experimental research. 
In our investigation obtained transformations for the transition from the local, moving coordinate system, to the laboratory, immobile. Such a transition allows, in particular, determining the velocity of the points of the material surface in the region of laser influence from the viewpoint of the observer. The obtained connection between local and laboratory coordinate systems makes it possible to link the results of theoretical calculations that are convenient to execute in the local system, with experimental observations executed in the laboratory system. Because of to the coordinate transformations, the problem solution makes it possible to follow up the near-surface changes during the destructive laser action. On the basis of coordinate transformations, the differential equation in partial derivatives is formulated in the paper. This makes it possible for process of development of a nanocractor on an irradiated surface to observing. The numerical simulation of the nanocrater formation with a given model form of an active laser pulse is presented. The performed test calculations correspond to experimental observation and theoretical ideas about the process of development of a corrosion crater under laser pulsed irradiation.