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Non-local density functional description of poly-para-phenylene vinylene (2007)
Journal Article
Zheng, G., Clark, S., Brand, S., & Abram, R. (2007). Non-local density functional description of poly-para-phenylene vinylene. Chinese Physics Letters, 24(3), 807-810. https://doi.org/10.1088/0256-307x/24/3/061

A fully non-local exchange-correlation formalism within the framework of density functional theory, known as the weighted density approximation (WDA), has been applied to the conjugated polymer poly-para-phenylene vinylene (PPV) and is shown to lead... Read More about Non-local density functional description of poly-para-phenylene vinylene.

Lattice dynamics of polyaniline and poly(p-pyridyl vinyline): First-principles determination (2006)
Journal Article
Zheng, G., Clark, S., Brand, S., & Abram, R. (2006). Lattice dynamics of polyaniline and poly(p-pyridyl vinyline): First-principles determination. Physical review B, 74(16), https://doi.org/10.1103/physrevb.74.165210

First-principles density functional studies of the dynamical properties of the conjugated polymers polyaniline and poly(p-pyridyl vinyline) are presented in this work. We have employed linear response within density functional perturbation theory, as... Read More about Lattice dynamics of polyaniline and poly(p-pyridyl vinyline): First-principles determination.

Molecular dynamics calculations of the thermal expansion properties and melting points of Si and Ge (2006)
Journal Article
Timon, V., Brand, S., Clark, S., & Abram, R. (2006). Molecular dynamics calculations of the thermal expansion properties and melting points of Si and Ge. Journal of Physics: Condensed Matter, 18(13), 3489-3498. https://doi.org/10.1088/0953-8984/18/13/016

The thermal expansion properties and melting points of silicon and germanium are calculated using molecular dynamics simulations within the density functional theory framework. An isothermal–isobaric (NPT) ensemble is considered in a periodic system... Read More about Molecular dynamics calculations of the thermal expansion properties and melting points of Si and Ge.

First-principles calculations of 2x2 reconstructions of GaN(0001) surfaces involving N, Al, Ga, In, and as atoms (2005)
Journal Article
Timon, V., Brand, S., Clark, S., Gibson, M., & Abram, R. (2005). First-principles calculations of 2x2 reconstructions of GaN(0001) surfaces involving N, Al, Ga, In, and as atoms. Physical review B, 72(3), https://doi.org/10.1103/physrevb.72.035327

The ab initio studies presented here employed a pseudopotential-plane-wave method in order to obtain the minimum-energy configurations of various 22 GaN0001 surfaces involving N, Al, Ga, In, and As atoms. Comparison of the various possible reconstruc... Read More about First-principles calculations of 2x2 reconstructions of GaN(0001) surfaces involving N, Al, Ga, In, and as atoms.

Ab initio dynamics study of poly-para-phenylene vinylene (2005)
Journal Article
Zheng, G., Clark, S., Tulip, P., Brand, S., & Abram, R. (2005). Ab initio dynamics study of poly-para-phenylene vinylene. The Journal of Chemical Physics, 123(2), Article 024904. https://doi.org/10.1063/1.1955516

We present an ab initio dynamics investigation within a density-functional perturbation theory framework of the properties of the conjugated polymer poly-para-phenylene vinylene (PPV) in both the isolated chain and crystalline states. The calculated... Read More about Ab initio dynamics study of poly-para-phenylene vinylene.

Theoretical adlayer surface morphology of wurtzite 2 × 2 reconstructions of the GaN (0001) surface (2005)
Journal Article
Timon, V., Brand, S., Clark, S., & Abram, R. (2005). Theoretical adlayer surface morphology of wurtzite 2 × 2 reconstructions of the GaN (0001) surface. Journal of Physics: Condensed Matter, 17(1), 17-26. https://doi.org/10.1088/0953-8984/17/1/002

In the first-principles calculations presented here we employ a density functional formalism using a pseudopotential plane-wave basis set in order to obtain the minimum energy configurations of various GaN(0001) 2 × 2 surfaces involving N atoms. The... Read More about Theoretical adlayer surface morphology of wurtzite 2 × 2 reconstructions of the GaN (0001) surface.

First-principles studies of the structural and electronic properties of poly-para-phenylene vinylene (2004)
Journal Article
Zheng, G., Clark, S., Brand, S., & Abram, R. (2004). First-principles studies of the structural and electronic properties of poly-para-phenylene vinylene. Journal of Physics: Condensed Matter, 16(47), 8609-8620. https://doi.org/10.1088/0953-8984/16/47/013

We present first-principles investigations of the structural and electronic properties of PPV in both the isolated chain and the crystalline state. The calculations are mainly based on the local density approximation within density functional theory.... Read More about First-principles studies of the structural and electronic properties of poly-para-phenylene vinylene.

Ab initio studies of strained wurtzite GaN surfaces (2004)
Journal Article
Timon, V., Brand, S., Clark, S., & Abram, R. (2004). Ab initio studies of strained wurtzite GaN surfaces. Journal of Physics: Condensed Matter, 16(4), 531-542. https://doi.org/10.1088/0953-8984/16/4/002

In GaN and other group III nitrides the considerable lattice mismatch with the substrates normally employed during growth, such as sapphire, 6H-SiC and ZnO, can lead to the presence of strain which may affect the surface properties. Here we have stud... Read More about Ab initio studies of strained wurtzite GaN surfaces.

Structure and electronic properties of FeSi2 (1998)
Journal Article
Clark, S., Al-Allak, H., Brand, S., & Abram, R. (1998). Structure and electronic properties of FeSi2. Physical review B, 58(16), 10389-10393. https://doi.org/10.1103/physrevb.58.10389

The nature of the band gap in the semiconducting material beta-FeSi2 is still under some dispute. Although most experimental results indicate the band gap to be direct, nb initio work generally reports the material to be an indirect semiconductor wit... Read More about Structure and electronic properties of FeSi2.

Screened Exchange Calculations of Semiconductor Band Structures
Presentation / Conference Contribution
Gibson, M. C., Clark, S. J., Brand, S., & Abram, R. A. (2004, July). Screened Exchange Calculations of Semiconductor Band Structures. Presented at 27th International Conference on the Physics of Semiconductors : ICPS-27., Flagstaff, Arizona

We have calculated the band structures of several group IV and III-V semiconductors from first principles. The technique we have employed is the screened exchange method, which is an extension of the commonly used Kohn-Sham density functional theory... Read More about Screened Exchange Calculations of Semiconductor Band Structures.