I have for many years studied how things break at the atomic scale.  Here is a movie of a stable crack in silicon produced by molecular dynamics.

Atomic study of fracture is not restricted however to molecular dynamics. Leonid Slepyan found in the 1980s that it was possible to solve dynamic crack problems at the atomic scale analytically, and I have spent years expanding and generalizing those solutions. They teach many fascinating lessons, resolve puzzles in fracture mechanics and pose new ones.

Here are some of the latest findings, work done with Jackie Jensen.
1) For analytically solvable models of crack motion in crystals, the boundary conditions on crack faces used since fracture mechanics began (shear and normal stresses on crack faces vanish) are not correct.
2) Limiting crack speeds are determined by a new pair of surface wave speeds
3) From a catalog of 160,000 analytical fracture solutions, depicted below, we find that intersonic and supersonic cracks are ubiquitous, depending on elastic properties and levels of dissipation, so long as crack-tip instabilities can be avoided.

 

This figure shows the results of finding 160,000 analytical solutions for crack motion at the atomic scale. The horizontal axis shows the ratio of longitudinal to transverse wave speed in the material and therefore lets one scan through all possible elastic properties of isotropic linear elastic solids. The vertical axis is crack speed in units of the transverse wave speed. White regions are stable cracks. The parameter \beta determines the level of dissipation. When it is 0.1, dissipation is small as for glass. When it is 1, dissipation is moderate, as for Plexiglas. When it is 10 or 100 dissipation is large as for rubber or hydrogels. It is in these latter systems that intersonic cracks have been observed in experiment, most recently by Wang, Shi, and Fineberg.

Publications:

M. Marder, “Breaking fast and slow,” Nat. Phys., vol. 20, no. 4, pp. 546–547, Apr. 2024, doi: 10.1038/s41567-024-02389-0.

M. Marder, “From cracks to atoms and back again,” Physics Today, vol. 77, no. 2, pp. 62–63, 2024, doi: 10.1063/pt.ihuk.frks.

M. Marder, “Cracks break the sound barrier,” Science, vol. 381, no. 6656, pp. 375–376, Jul. 2023, doi: 10.1126/science.adj0963.

M. Marder, “Mode I Fracture in Triangular Lattice.” Texas Data Repository, Apr. 06, 2019. doi: 10.18738/T8/WIVA49.

M. Marder, “Slepyan’s dynamic contribution to studies of fracture,” Philosophical Transactions of the Royal Society A, vol. 377, no. 2156, p. 20190098, 2019, doi: 10.1098/rsta.2019.0098.

M. Marder, “Particle methods in the study of fracture,” Int J Fract, vol. 196, no. 1, pp. 169–188, Nov. 2015, doi: 10.1007/s10704-015-0070-x.

C. Behn and M. Marder, “The transition from subsonic to supersonic cracks,” Philosophical Transactions A, vol. 373, p. 10.1098/rsta.2014.0122/1-15, 2015, doi: 10.1098/rsta.2014.0122.

C. H. Chen, H. P. Zhang, J. Niemczura, K. Ravi-Chandar, and M. Marder, “Scaling of crack propagation in rubber sheets,” Europhysics Letters, vol. 96, p. 36009/1–6, 2011, doi: 10.1209/0295-5075/96/36009.

T. M. Guozden, E. A. Jagla, and M. Marder, “Supersonic cracks in lattice models,” Int J Fract, vol. 162, no. 1, pp. 107–125, Mar. 2010, doi: 10.1007/s10704-009-9426-4.

E. Bouchbinder, J. Fineberg, and M. Marder, “Dynamics of simple cracks,” Annual Reviews of Condensed Matter Physics, vol. 1, pp. 371–395, 2010, doi: 10.1146/annurev-conmatphys-070909-104019.

H. P. Zhang, J. Niemczura, G. Dennis, K. Ravi-Chandar, and M. Marder, “Toughening effect of strain-induced crystallites in natural rubber,” Physical Review Letters, vol. 102, no. 24, p. 245503, 2009, doi: 10.1103/PhysRevLett.102.245503.

M. Marder, “Shock-Wave Theory for Rupture of Rubber,” Phys. Rev. Lett., vol. 94, no. 4, p. 048001, Jan. 2005, doi: 10.1103/PhysRevLett.94.048001.

M. Marder, “Effects of atoms on brittle fracture,” International Journal of Fracture, vol. 130, no. 2, pp. 517–555, Nov. 2004, doi: 10.1023/B:FRAC.0000049501.35598.87.

P. J. Petersan, R. D. Deegan, M. Marder, and H. L. Swinney, “Cracks in rubber under tension exceed the shear wave speed,” PRL, vol. 93, p. 015504/1–4, 2004.

M. Marder, “Cracks cleave crystals,” Europhysics Letters, vol. 63, pp. 364–370, 2004, doi: 10.1209/epl/i2003-10254-4.

R. D. Deegan et al., “Wavy and rough cracks in silicon,” Physical Review E, vol. 67, p. 66209, 2003, doi: 10.1103/PhysRevE.67.066209.

R. D. Deegan, P. Petersan, M. Marder, and H. L. Swinney, “Oscillating fracture paths in rubber,” Physical Review Letters, vol. 88, p. 14304, 2002, doi: 10.1103/PhysRevLett.88.014304.

E. Gerde and M. Marder, “Friction and fracture,” Nature, vol. 413, pp. 285–288, 2001, doi: 10.1038/35095018.

M. Marder, “Molecular dynamics of cracks,” Computers in Science and Engineering, vol. 1, pp. 48–55, 1999, doi: 10.1109/5992.790587.

D. Holland and M. Marder, “Cracks and atoms,” Advanced Materials, vol. 11, pp. 793–806, 1999, doi: 10.1103/PhysRevLett.82.3823.

J. Fineberg and M. Marder, “Instability in dynamic fracture,” Physics Reports, vol. 313, pp. 1–108, 1999, doi: 10.1016/S0370-1573(98)00085-4.

M. Marder, “Energies of a kinked crack line,” Journal of Statistical Physics, vol. 93, pp. 511–525, 1998, doi: 10.1023/B:JOSS.0000033239.22129.c1.

M. Marder, “Adiabatic equation for cracks,” Philosophical Magazine B, vol. 78, pp. 203–214, 1998.

D. Holland and M. Marder, “Ideal brittle fracture of silicon studied with molecular dynamics,” Physical Review Letters, vol. 80, pp. 746–749, 1998.

J. Hauch and M. Marder, “Energy balance in dynamic fracture, investigated by a potential drop technique,” International Journal of Fracture, vol. 90, pp. 133–151, 1998.

M. Marder and J. Fineberg, “How things break,” Physics Today, vol. 49, pp. 24–29, 1996, doi: 10.1063/1.881515.

M. Marder, “Statistical mechanics of cracks.,” Physical Review E, vol. 54, pp. 3442–3454, 1996, doi: 10.1103/PhysRevE.54.3442.

M. Marder and S. Gross, “Origin of crack tip instabilities,” Journal of the Mechanics and Physics of Solids, vol. 43, pp. 1–48, 1995, doi: 10.1016/0022-5096(94)00060-I.

M. Marder, “Instability of a crack in a heated strip,” Physical Review E, vol. 49, pp. R51–R54, 1994.

M. Marder and X. Liu, “Instability in lattice fracture,” Physical Review Letters, vol. 71, pp. 2417–20, 1993, doi: 10.1103/PhysRevLett.71.2417.

S. Gross, J. Fineberg, M. Marder, M. W D, and H. L. Swinney, “Acoustic emissions from rapidly moving cracks,” Physical Review Letters, vol. 71, pp. 3162–3165, 1993, doi: 10.1103/PhysRevLett.71.3162.

J. Fineberg, S. Gross, M. Marder, and H. L. Swinney, “Instability in the propagation of fast cracks,” Physical Review B-Condensed Matter, vol. 45, pp. 5146–54, 1992, doi: 10.1103/PhysRevB.45.5146.

M. Marder, “New dynamical equation for cracks,” Physical Review Letters, vol. 66, pp. 2484–7, 1991, doi: 10.1103/PhysRevLett.66.2484.

X. Liu and M. Marder, “The energy of a steady-state crack in a strip,” Journal of the Mechanics and Physics of Solids, vol. 39, pp. 947–961, 1991, doi: 10.1016/0022-5096(91)90013-E.

J. Fineberg, S. P. Gross, M. Marder, and H. L. Swinney, “Instability in dynamic fracture,” Physical Review Letters, vol. 67, pp. 457–60, 1991, doi: 10.1103/PhysRevLett.67.457.