Alejandro Strachan

Strain relaxation in Si/Ge/Si nanoscale bars from molecular dynamics simulations (2009)

Park, Yumi, Atkulga, Hasan, Grama, Ananth, Strachan, Alejandro

We use molecular dynamics (MD) with the reactive interatomic potential ReaxFF to characterize the local strains of epitaxial Si/Ge/Si nanoscale bars as a function of their width and height. While the...

Coarse grain modeling of spall failure in molecular crystals: role of intra-molecular degrees of freedom (2009)

Lynch, Karen, Thompson, Alexander, Strachan, Alejandro

We use a recently developed thermodynamically accurate mesodynamical method (Strachan and Holian 2005 Phys. Rev. Lett. 94 014301) where groups of atoms are represented by mesoparticles to...

Electronic structure and transport in silicon nano-structures with non-ideal bonding environments (2008)

Palaria, Amritanshu, Klimeck, Gerhard, Strachan, Alejandro

As semiconductor devices scale down, the role of surfaces and interfaces becomes increasingly important. This effort seeks to develop methods for analysis of nano-structures, including the effect of...

Structures and Energetics of Si Nanotubes from Molecular Dynamics and Density Functional Theory (2008)

Palaria, Amritanshu, Klimeck, Gerhard, Strachan, Alejandro

We use molecular dynamics (MD) with a first principles-based force field (ReaxFF) and density functional theory (DFT) to predict the atomic structure, energetics and elastic propoerties of Si...

Reactive Force Fields Based on Quantum Mechanics for Applications to Materials at Extreme Conditions (2006)

Zybin, Sergey V., Chenoweth, Kimberley, Zhang, Luzheng, Han, Si-Ping, Strachan, Alejandro, ...

Understanding the response of energetic materials (EM) to thermal or shock loading at the atomistic level demands a highly accurate description of the reaction dynamics of multimillion-atom systems...

Reactive Force Fields Based on Quantum Mechanics for Applications to Materials at Extreme Conditions (2006)

Zybin, Sergey V., Chenoweth, Kimberley, Zhang, Luzheng, Han, Si-Ping, Strachan, Alejandro, ...

Understanding the response of energetic materials (EM) to thermal or shock loading at the atomistic level demands a highly accurate description of the reaction dynamics of multimillion-atom systems...

Large electrostrictive strain at gigahertz frequencies in a polymer nanoactuator: Computational device design (2005)

Strachan, Alejandro

Using molecular dynamics with a first-principles-based force field (denoted MSXX), we show that large electrostrictive strains (similar to 5%) at extremely high frequencies (over similar to 10^(9)...

Thermal decomposition of RDX from reactive molecular dynamics (2005)

Strachan, Alejandro, Kober, Edward M., Oxgaard, Jonas

We use the recently developed reactive force field ReaxFF with molecular dynamics to study thermal induced chemistry in RDX [cyclic-[CH2N(NO2)]3] at various temperatures and densities. We find that...

Density Functional Theory and Molecular Dynamics Studies on Energetics and Kinetics for Electro-Active Polymers: PVDF and P(VDF-TrFE) (2004)

Su, H. B., Strachan, Alejandro, Goddard III, William A.

We use first principles methods to study static and dynamical mechanical properties of the ferroelectric polymer Poly(vinylidene fluoride) (PVDF) and its copolymer with trifluoro ethylene (TrFE). We...

Density functional theory and molecular dynamics studies of the energetics and kinetics of electroactive polymers: PVDF and P(VDF-TrFE) (2004)

Su, Haibin, Strachan, Alejandro

We used first principles methods to study static and dynamical mechanical properties of the ferroelectric polymer poly(vinylidene fluoride) (PVDF) and its copolymer with trifluoro ethylene (TrFE). We...

Initial Chemical Events in the Energetic Material RDX under Shock Loading: Role of Defects (2004)

Strachan, Alejandro

We use the recently developed reactive force field ReaxFF with molecular dynamics (MD) to study the role of voids on the initial chemical events in the high-energy material RDX under shock loading....

Atomistic simulations of kinks in 1/2a screw dislocations in bcc tantalum (2003)

Wang, Guofeng, Strachan, Alejandro, Çağin, Tahir

Two types of equilibrium core structures (denoted symmetric and asymmetric) for 1/2a screw dislocations in bcc metals have been found in atomistic simulations. In asymmetric (or polarized) cores, the...

Maximum superheating and undercooling: Systematics, molecular dynamics simulations, and dynamic experiments (2003)

Luo, Sheng-Nian, Ahrens, Thomas J., Çağin, Tahir, Strachan, Alejandro, Swift, Damian C.

The maximum superheating and undercooling achievable at various heating (or cooling) rates were investigated based on classical nucleation theory and undercooling experiments, molecular dynamics (MD)...

Role of core polarization curvature of screw dislocations in determining the Peierls stress in bcc Ta: A criterion for designing high-performance materials (2003)

Wang, Guofeng, Strachan, Alejandro, Çağin, Tahir

We use a family of embedded atom model potentials all based on accurate quantum-mechanical calculations to study the relation between Peierls stress and core properties of the 1/2a‹111› screw...

Ab initio and finite-temperature molecular dynamics studies of lattice resistance in tantalum (2002)

Segall, D. E., Strachan, Alejandro, Ismail-Beigi, Sohrab, Goddard III, William A., Arias, T. A.

This manuscript explores the apparent discrepancy between experimental data and theoretical calculations of the lattice resistance of bcc tantalum. We present the first results for the temperature...

First Principles Force Field for Metallic Tantalum (2002)

Strachan, Alejandro, Cagin, Tahir, Gulseren, Oguz, Mukherjee, Sonali, Cohen, Ronald E., Goddard III, William A.

We propose a general strategy to develop accurate Force Fields (FF) for metallic systems derived from ab initio quantum mechanical (QM) calculations; we illustrate this approach for tantalum. As...

Accurate Calculations of the Peierls Stress in Small Periodic Cells (2001)

Segall, D. E., Arias, T. A., Strachan, Alejandro, Goddard III, William A.

The Peierls stress for a [111]-screw dislocation in bcc Tantalum is calculated using an embedded atom potential. More importantly, a method is presented which allows accurate calculations of the...

Reply to “Comment on ‘Phase diagram of MgO from density-functional theory and molecular-dynamics simulations’” (2001)

Strachan, Alejandro, Çağin, Tahir

In answer to a Comment by Belonoshko [Phys. Rev. B 63, 096101 (2001)], we show that the B1-liquid melting curve of MgO obtained using two-phase simulations is in good agreement with the published one...

Critical behavior in spallation failure of metals (2001)

Strachan, Alejandro, Çağin, Tahir

Using molecular dynamics with an accurate many-body potential, we studied the rapid expansion of Ta metal following the high compression (50 to 100 GPa) induced by high velocity (2 to 4 km/s) impact....

Phase diagram of MgO from density-functional theory and molecular-dynamics simulations (1999)

Strachan, Alejandro, Çağin, Tahir

We use first-principles methods (no empirical parameters) to establish the phase diagram for the B1(NaCl), B2(CsCl), and liquid phases of MgO. We used density-functional theory with the generalized...

The Phase Diagram of MgO from Density Functional Theory and Molecular Dynamics Simulations (1999)

Alejandro Strachan, Ro Strachan, Tahir Cagin

We use first principles methods (no empirical parameters) to establish the phase diagram for the B1(NaCl), B2(CsCl), and liquid phases of MgO. We used density functional theory (DFT) with the...