Mikko P. Haataja (PhD, McGill University) 
    Associate Professor

Department of Mechanical and Aerospace Engineering , Princeton University, Olden Street, Princeton, NJ 08544, USA.

Room: D-404C
Tel: 1-609-258 9126
Fax: 1-609-258 5877

Welcome to the homepages of the COMBO (COmputational Materials & BiOphysics) group! I am the leader of a group of computational and theoretical materials scientists, whose research focuses on physics of materials and biophysics. The underlying theme of our research can be stated as "mesoscale modeling of hard and soft matter systems". Our research activities in hard matter systems are currently supported by the National Science Foundation (NSF) and Department of Energy (DOE), while support for the soft matter activities are provided by the NSF. Current work includes studies of microstructure formation during solid-solid phase transformations and solidification, dislocation dynamics, mechanical properties of metallic glasses, and compositional domain formation on surfaces for catalysis applications. More recently, my group has extended some of the coarse-grained methods developed in hard matter systems to address important biophysical phenomena in soft matter systems, such as structure and dynamics of compositional lipid microdomains in membranes. To give you a flavor of my research interests, a brief description of some of the problems I've been working on recently can be found below. The list of recent papers also includes links to PDF versions of the published/submitted papers.



One problem of long-standing interest to me has to do with extending the time scales of atomic scale simulations. To this end, several years ago, we introduced a continuum "phase-field crystal model" capable of simulating crystalline phases with atomic scale spatial resolution across diffusive time scales [for details, see K. R. Elder et al., PRL 88, 245701 (2002)]. Together with Peter Stefanovic and Nick Provatas, we have extended this method to include elastic relaxation through the propagation of "quasi-phonons" [Stefanovic et al., PRL 95, 225504 (2006)]. More recently, we have studied the formation of strain-induced compositional domains on metallic surfaces [Muralidharan and Haataja, Phys. Rev. Lett. (2010)]. The figures below illustrate the behavior of CoAg film on Ru(0001) surface. Left panel: symmetric composition. Middle panel: Ag-rich composition. Note the coexistence between a nanoscale alloy and a dislocated pure Ag phase. Right panel: Co-rich composition. Note the coexistence between a pseudomorphic alloy phase and Co-rich phase.

Additionally, we have investigated the growth of multilayer thin film systems using the PFC approach. Left panel: so-called herringbone pattern emerges from the deposition of 1 ML of Ag on Ru(0001) substrate. Middle panel: Nucleation of islands on top of misfit dislocations (shown in red circles) within ML1. Here, ML2 atoms (shown in blue) have a misfit relative to both Ag and Ru. [In other words, we have a A/B/C-type multilayer system.] Right panel: A/B/A-type growth. Here, Ru atoms comprising ML2 form elongated islands as directed by the herringbone patterns in ML1.

Dislocations in crystalline pure metals and alloys continue to be a topic of national importance and interest, as the development of novel structural materials requires the development of physically-based, effective constitutive equations at the mesoscale. To this end, we have employed a parallel, three-dimensional level-set code to simulate the dynamics of isolated dislocation lines and loops in an obstacle-rich environment. This system serves as a convenient prototype of those in which extended, one-dimensional objects interact with obstacles and the out-of-plane motion of these objects is key to understanding their pinning-depinning behavior. In contrast to earlier models of dislocation motion, we incorporate long-ranged interactions among dislocation segments and obstacles to study the effect of climb on dislocation dynamics in the presence of misfitting penetrable obstacles/solutes, as embodied in an effective climb mobility. Our main observations are as follows. First, increasing climb mobility leads to more effective pinning by the obstacles, implying increased strengthening. Second, decreasing the range of interactions significantly reduces the effect of climb. The dependence of the critical stress on obstacle concentration and misfit strength is also explored and compared with existing models. In particular, our results are shown to be in reasonable agreement with the Friedel-Suzuki theory. The figures below illustrate dislocation morphologies at low, intermediate, and high external stresses, as well as the effective glide mobility extracted from the simulations. Note the extensive deformation of the dislocation line at intermediate values of the external stress. [Chen et al., Phys. Rev. B 81, 054104 (2010).]

We are also interested in developing a mechanistic understanding of the migration of low angle grain boundaries (LAGB) in terms of the collective dynamics of the constituent dislocations. The image below left displays an LAGB of mixed character during steady-state migration driven by external stress, while the figure on the right displays the steady-state migration velocity of the GB as a function of external stress and dislocation climb mobility. [Lim, Srolovitz, Cai, and Haataja, in preparation.]

We have also recently investigated mechanical properties of metallic glasses and metallic glass-(nano)crystalline material composites through simulations of a novel phase-field model. The figures below illustrate the deformation of such a composite, in which the ductile particles are spherical. Left panel: representative microstructure. Middle panel: deformed shape and local shear strain prior to shear band nucleation. Right panel: deformed shape and local shear strain after shear band nucleation. [Abdeljawad and Haataja, Phys. Rev. Lett. (2010)]
Additionally, we have investigated the role of particle morphology on mechanical properties of BMG composites. The figures below illustrate the deformation of a composite, in which the ductile particles are ramified. Left panel: representative microstructure. Middle panel: deformed shape and local shear strain prior to shear band nucleation. Note the existence of incipient shear bands emanating from the tips of the dendrites, and constrained between dendrites. Right panel: deformed shape and local shear strain after shear band nucleation and propagation. [Abdeljawad et al., Applied Physics Letters (2011)]

We have also recently worked on developing physically-based models which explain morphologies of wurtzite nanoribbons. In particular, such nanoribbons have been experimentally observed to spontaneously bend into nanorings or nanoarcs. Our theory suggests that bending is controlled by dopant density, spontaneous polarization, and nanoribbon thickness. The figures below display the crystal structure of ZnO and predicted nanoribbon curvature as a function of thickness H and dopant density [C. Majidi, Z. Chen, D. J. Srolovitz, and M. Haataja, JMPS (2010)].

We are also interested in understanding and predicting the spatio-temporal evolution of morphologies, deformation, and damage in multiphase, multicomponent materials for energy conversion and storage under extended use. The figures below display continuum simulations of stress evolution and damage accumulation due to redox reaction in a Solid Oxide Fuel Cell anode (Ni-YSZ). In the figures below, Ni phase is shown in orange, YSZ in green, and pore phase in white. Leftmost panel: experimentally obtained Ni-YSZ microstructure employed in the simulations. Panel 2nd from left: spatial distribution of accumulated damage during stress evolution. Panel 2nd from right: two-dimensional cross-section of microstructure. Rightmost panel: regions of large tensile stress within the YSZ phase are localized within highly constrained YSZ domains. [F. Abdeljawad, G. J. Nelson, W. K. S. Chiu, and M. Haataja, work in progress].

We have recently launched a research effort in soft condensed matter systems. More specifically, we are currently investigating (1) self-organization and non-equilibrium dynamics in lipid bilayers, (2) molecular structure and properties of lipid bilayers, and (3) self-assembly of detergents in bulk and on surfaces. The first figure from the left shows a typical microstructure in a three component lipid bilayer undergoing phase separation in the presence of non-equilibrium flux of lipid to and from the monolayer in view. This "lipid recycling" leads to a steady-state where the domains attain a characteristic size dependent on the recycling rate. We argue that this recycling-induced steady-state can explain the presence of the elusive "lipid rafts" thought to exist in the mammalian plasma membrane [Fan et al., PRL 2008]. The middle frame demonstrates the effects of spatially-varying recycling rate on domain formation. In particular, rapid changes in the local recycling rate may lead to emergence of extended, transient rafts. Upon homogenizing the recycling rate, the membrane microstructure becomes homogeneous, as shown in the panel on the right [Fan et al., PRE 2010].
We have also developed a comprehensive classification scheme to experimentally distinguish between competing theoretical models for raft formation [Fan et al, PRL 2010]. The method is based on quantifying the spatio-temporal fluctuations of the raft domains via speckle autocorrelation function and static structure factor; the combination of the two provides the means to identify the operative raft formation mechanism in living cells. Below, typical microstructures corresponding to the five existing theoretical models are displayed (I - critical fluctuations [Veatch et al., 2008]; II - pinning by immobile membrane proteins [Yethiraj & Weisshaar, 2007]; III - stochastic recycling above critical point [Edidin, 1999]; IV - stochastic recycling below the critical point [Fan, Sammalkorpi, and Haataja]; and V - coupling to lipid reservoir [Foret, 2005]).
The corresponding data for the temporal decay of fluctuations and static structure factor are shown below. Collecting data over a broad range of wavenumbers allows one to experimentally distinguish between the raft formation scenarios.
We have also investigated the role of membrane and exterior solvent hydrodynamics on membrane critical dynamics [Haataja, PRE (2009)] and coarsening dynamics [Fan, Han, and Haataja, J. Chem. Phys. (2010)]. The two snapshots from the left below illustrate the coupling between compositional dynamics and membrane hydrodynamic flow fields, while the snapshot on the right displays the flow fields induced within the solvent due to compositional membrane evolution; this flow field subsequently back-reacts with the membrane flow field and influences the phase separation process. In particular, we have demonstrated that the 2D nature of the membrane flow fields coupled to a 3D exterior fluid gives rise to novel coarsening behavior.
Finally, the leftmost figure displays a snapshot from a simulation where micelle formation takes place. In addition to lipids and detergents, we are interested in the behavior of synthetic molecular switches in biology. To this end, we have constructed physically-based models for the tether length dependence of signal integration proteins, shown schematically in the figure on the right [Van Valen, Haataja, and Phillips, Biophys. J. 96, 1275 (2009)].





[8] T. Han and M. Haataja, "Compositional interface dynamics in symmetric and asymmetric planar lipid bilayer membranes", submitted to Soft Matter (2012).

[7] S. Lee, S. Muralidharan, A. Woll, M. Loth, Z. Li, J. Anthony, M. Haataja, and Y.-L. Loo, "Understanding heterogeneous nucleation in solution-processed, organic semiconductor thin films", Chemistry of Materials 24, 2920 (2012).

[6] S. Muralidharan, R. Khodadad, E. Sullivan, and M. Haataja, "Multilayer Thin Film Growth on Crystalline and Quasicrystalline Surfaces: A Phase-field Crystal Study", Phys. Rev. B 85, 245428 (2012).

[5] F. Abdeljawad, G. Nelson, W. K. S. Chiu, and M. Haataja, "Redox Instability, Mechanical Deformation, and Heterogeneous Damage Accumulation in Solid Oxide Fuel Cell Anodes", J. Appl. Phys. 112, 036102 (2012).

[4] Z. Chen, Q. Guo, C. Majidi, W. Chen, D. J. Srolovitz, and M. Haataja, "Nonlinear geometric effects in mechanical bistable morphing structures", Phys. Rev. Lett. 109, 114302 (2012).

[3] Z. Chen, C. Majidi, D. J. Srolovitz, and M. Haataja, "Continuum Elasticity Theory Approach for Spontaneous Bending and Helicity of Ribbons Induced by Mechanical Anisotropy", submitted to Proc. R. Soc. (2012).

[2] S. Jia, M. Haataja, and J. W. Fleischer, "Rayleigh-Taylor instability in nonlinear Schroedinger flow", New Journal of Physics 14, 075009 (2012).

[1] A. Lim, M. Haataja, W. Cai, and D. J. Srolovitz, "Stress-driven migration of simple low-angle mixed grain boundaries", Acta Materialia 60, 1395 (2012).



[5] T. Han and M. Haataja, "Comprehensive analysis of compositional interface fluctuations in planar lipid bilayer membranes", Phys. Rev. E 84, 051903 (2011). (PDF)

[4] M. Sammalkorpi, S. Sanders, A. Z. Panagiotopoulos, M. Karttunen, and M. Haataja, "Simulations of micellization of sodium hexyl sulfate", J. Phys. Chem. B 115, 1403 (2011). (PDF)

[3] Z. Chen, C. Majidi, D. J. Srolovitz, and M. Haataja, "Tunable Helical Ribbons", Applied Physics Letters 98, 011906 (2011). (PDF)

[2] F. Abdeljawad, M. Fontus, and M. Haataja, "Ductility of Bulk Metallic Glass Composites: Microstructural Effects", Applied Physics Letters 98, 031909 (2011). (PDF)

[1] J. J. Hoyt and M. Haataja, "Continuum model of irradiation-induced spinodal decomposition in the presence of dislocations", Phys. Rev. B 83, 174106 (2011). (PDF)



[10] J. Fan, M. Sammalkorpi, and M. Haataja, "Influence of Non-Equilibrium Lipid Transport, Membrane Compartmentalization, and Membrane Proteins on the Lateral Organization of the Plasma Membrane", Phys. Rev. E 81, 011908 (2010). (PDF)

[9] J. Fan, M. Sammalkorpi, and M. Haataja, "Lipid microdomains: Structural correlations, fluctuations, and formation mechanisms", Phys. Rev. Lett. 104, 118101 (2010). (PDF)

[8] J. Fan, M. Sammalkorpi, and M. Haataja, "Formation and Regulation of Lipid Microdomains in Cell Membranes: Theory, Modeling, and Speculation", FEBS Letters 584, 1648 (2010). (PDF)

[7] J. Fan, T. Han, and M. Haataja, "Hydrodynamic effects on spinodal decomposition kinetics in planar lipid bilayer membranes", J. Chem. Phys. 133, 235101 (2010). (PDF)

[6] C. Majidi, Z. Chen, D. J. Srolovitz, and M. Haataja, "Theory for the Spontaneous Bending of Piezoelectric Nanoribbons: Mechanics, Spontaneous Polarization, and Space Charge Coupling", Journal of Mechanics and Physics of Solids 58, 73 (2010). (PDF)

[5] C. Majidi, M. Haataja, and D. J. Srolovitz, "Analysis and design principles for shear-mode piezoelectric energy harvesting", Smart Materials and Structures 19, 055027 (2010). (PDF)

[4] Z. Chen, K. T. Chu, D. J. Srolovitz, J. M. Rickman, and M. Haataja, "Dislocation climb strengthening in systems with immobile obstacles: Three-dimensional level-set simulation study", Phys. Rev. B 81, 054104 (2010). (PDF)

[3] F. Abdeljawad and M. Haataja, "Continuum modeling of bulk metallic glasses and composites", Phys. Rev. Lett. 105, 125503 (2010). (PDF)

[2] M. Haataja, L. Granasyi, and H. Lowen, "Classical density functional theory methods in soft and hard matter", J. Phys. Cond. Matt. 22, 360301 (2010). (PDF)

[1] S. Muralidharan and M. Haataja, "Phase-field crystal modeling of compositional domain formation in ultrathin films", Phys. Rev. Lett. 105, 126101 (2010). (PDF)



[8] M. Haataja, "Critical Dynamics in Multicomponent Lipid Membranes", Phys. Rev. E 80, 020902(R) (2009). (PDF)

[7] D. Van Valen, M. Haataja, and R. Phillips, "Tether length dependence of signal integration proteins", Biophysical Journal 96, 1275 (2009). (PDF)

[6] A. Jusufi, A.-P. Hynninen, M. Haataja, and A. Z. Panagiotopoulos, "Electrostatic screening and charge correlation effects in micellization of ionic surfactants", JPCB 113, 6314 (2009). (PDF)

[5] M. Karttunen, M. Haataja, M. Saily, I. Vattulainen, and J. Holopainen, "Lipid domain morphologies in Langmuir monolayer binary systems", Langmuir 25, 4595 (2009). (PDF)

[4] M. Sammalkorpi, M. Karttunen, and M. Haataja, "Ionic surfactants in saline solutions: Sodium Dodecyl Sulphate (SDS) in the presence of excess NaCl or CaCl2", JPCB 113, 5863 (2009). (PDF)

[3] A. T. Lim, M. Haataja, and D. J. Srolovitz, "Low-Angle Grain Boundary Migration in the Presence of Extrinsic Dislocations", Acta Materialia 57, 5013 (2009). (PDF)

[2] P. Stefanovic, M. Haataja, and N. Provatas, "Phase field crystal study of deformation and plasticity in nanocrystalline materials", Phys. Rev. E 80, 046107 (2009). (PDF)

[1] B. E. Sonday, M. Haataja, and Y. Kevrekidis, "Coarse-graining the dynamics of a driven interface in the presence of mobile impurities: Effective description via diffusion maps", Phys. Rev. E 80, 031102 (2009). (PDF)



[5] M. Sammalkorpi, A. Z. Panagiotopoulos, and M. Haataja, "Structure and Dynamics of Surfactant and Hydrocarbon Aggregates on Defective Graphite: A Molecular Dynamics Simulation Study", J. Phys. Chem B 112, 12954 (2008). (PDF)

[4] M. Sammalkorpi, M. Karttunen, and M. Haataja, "Micelle fission via surface instability and formation of an interdigitating stalk", J. Am. Chem. Soc. 130, 17977 (2008). (PDF)

[3] J. Rickman, M. Haataja, and R. LeSar, "Impact of Obstacles on Dislocation Patterning", Phys. Rev. B 77, 174501 (2008). (PDF)

[2] M. Sammalkorpi, A. Z. Panagiotopoulos, and M. Haataja, "Structure and dynamics of surfactant and hydrocarbon aggregates on graphite: a molecular dynamics study", J. Phys. Chem. B 112, 2915 (2008). (PDF)

[1] J. Fan, M. Sammalkorpi, and M. Haataja, "Domain formation in the plasma membrane: Roles of non-equilibrium lipid transport and membrane proteins", Phys. Rev. Lett. 100, 178102 (2008). (PDF)



[2] S. Sreekala and M. Haataja, "Recrystallization kinetics: A coupled coarse-grained dislocation density and phase-field approach", Phys. Rev. B 76, 094109 (2007). (PDF)

[1] M. Sammalkorpi, M. Karttunen, and M. Haataja, "Structural properties of ionic detergent aggregates: a large-scale molecular dynamics study of sodium dodecyl sulfate", J. Phys. Chem. B 111, 11722 (2007). (PDF)



[2] P. Stefanovic, M. Haataja, and N. Provatas, "Phase-field Crystals with Elastic Interactions", Phys. Rev. Lett. 96, 225504 (2006). (PDF)

[1] J. Fan, M. Greenwood, M. Haataja, and N. Provatas, "Phase-field simulations of rapid solidification of binary alloys", Phys. Rev. E 74, 031602 (2006). (PDF)



[2] F. Leonard and M. Haataja, "Alloy destabilization by dislocations", Appl. Phys. Lett. 86, 181909 (2005). (PDF)

[1] M. Haataja, J. Mahon, N. Provatas, and F. Leonard, "Scaling of domain size during spinodal decomposition: dislocation discreteness and mobility effects", Appl. Phys. Lett. 87, 251901 (2005). (PDF)

  2001-2004: Selected publications


[8] M. Greenwood, M. Haataja, and N. Provatas, "Crossover scaling of wavelength selection in directional solidification of binary alloys", Phys. Rev. Lett. 93, 246101 (2004). (PDF)

[7] M. Haataja, D. J. Srolovitz, and Y. G. Kevrekidis, "Apparent hysteresis in a driven system with self-organized drag", Phys. Rev. Lett. 93, 155502 (2004). (PDF)

[6] M. Haataja and F. Leonard, "Spinodal decomposition in the presence of mobile dislocations", Phys. Rev. B 69, 081201 (2004). (PDF)

[5] N. Provatas, Q. Wang, M. Haataja, and M. Grant, "Seaweed to Dendrite Transition in Directional Solidification", Phys. Rev. Lett. 91, 155502 (2003). (PDF)

[4] M. Haataja and D. J. Srolovitz, "Morphological stability and additive-induced stabilization in Electrodeposition", Phys. Rev. Lett. 89, 215509 (2002). (PDF)

[3] K. Elder, M. Katakowski, M. Haataja, and M. Grant, "Modeling Elasticity in crystal growth", Phys. Rev. Lett. 88, 245701 (2002). (PDF)

[2] M. Haataja J. Muller, A. D. Rutenberg, and Martin Grant, "Dislocations and morphological instabilities: Continuum modeling of misfitting heteroepitaxial films", Phys. Rev. B 65, 165414 (2002). (PDF)

[1] M. Haataja J. Muller, A. D. Rutenberg, and Martin Grant, "Dynamics of dislocations and surface instabilities in misfitting heteroepitaxial films", Phys. Rev. B 65, 035401 (2001). (PDF)



Current members of the COMBO group are Mr. Fadi Abdeljawad (graduate student), Mr. Tao Han (graduate student), Mr. Alireza Zaheri (graduate student), Mr. Ryan Davis (graduate student), and Ms. Alta Fang (graduate student).



Alumni members of the COMBO group are Dr. Jihee Kim (post-doc; now at Rutgers), Dr. Maria Sammalkorpi (post-doc; now at Aalto University), Dr. Carmel Majidi (post-doc; now at Carnegie Mellon University), Dr. Sreekala Subbulakshmi (post-doc), Dr. Kevin Chu, Dr. Lisa Manning (post-doc; now at Syracuse University), Dr. Jun Fan (graduate student; now at Univ. Chicago), Dr. Zi Chen (graduate student; now at Wash. U. St. Louis), Dr. Srevatsan Muralidharan (graduate student; now at Northwestern Univ.), Dr. Adele Lim (graduate student; now at IHPC, Singapore), Mr. Jordan Vincent (REU student), Mr. Jaime Osorio (REU student), Mr. Evan Randles (REU student), and Mr. James Martino (MAE summer student).



We have active collaborations with several groups: Prof. Nikolas Provatas at McMaster Univ. on phase-field modeling of phase transformations, Prof. Mikko Karttunen at UWO on physics and mechanics of lipid bilayers, Dr. Jeff Rickman at Lehigh on dislocation dynamics, Dr. Francois Leonard at Sandia on continuum-field dislocation dynamics, Prof. Rob Phillips on signaling pathways in cells, and Prof. David Srolovitz on level set methods in dislocation dynamics.



I am looking for a graduate student interested in studying interdisciplinary problems, ranging from the effects of dislocations on microstructure evolution to physics of biomolecules and membranes. Drop me a line if you are interested!

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