Postdoctoral Research Associate,
Computational Chemical Sciences Group,
Computer Science and Mathematics Division

Education, Professional Experience, Activities, and Honors:

Sefa Dag is postdoctoral research associate at the Oak Ridge National Laboratory  (ORNL) with the computational Chemical Science Group in the Computer Science and Mathematics and Center of Nanoscale Materials Science Divisions.  He  received his B.S. degree   in 1998 with first-class honors degree. For his graduate studies he has preferred the Physics department of Bilkent University receiving his M.Sc. degree in 2000. He pursued his Ph.D. degree at the same department. He received his Ph.D. from Bilkent University Physics Department in 2005. Both his M.Sc. and Ph.D. theses work are carried out under the supervision of Professor Salim Ciraci in the area of theoretical Condensed Matter Physics and Nanoscience. His intensive research efforts on nanotubes and nanowires has revealed a variety of properties which make important contributions to the fields of nanoscience and nanotechnology. The main objective of his research in these fields is to find new modifications to the pristine nanotube and nanowires to render them functionally active for the various applications.  His current research is related with the catalytic reactions on the TiO₂ surface, physical properties of 2D and 3D carbon nanotube grid structures and Scanning tunneling Microscopy simulations. He is doing his research with the supervision of Vincent Meunier.    Sefa Dag has more than 23 published papers in internationally recognized journals. He is also invited to give talks at the international conferences.
 

Interests and Expertise: Theoretical and computational physics, nanotubes, scanning tunneling microscopy, tribology.

Relevant Publications:

1.  “Ab-Initio temperature  dependent  studies of the homoepitaxial growth on  Si(001) surface”, S. Dag, S. Ciraci, C. Kilic, C. Y. Fong,  Surf. Sci. 479, 109-120  (2001).

 2.   “Oxygenation of carbon nanotubes: Atomic structure, energetics, and electronic structure “, S. Dag, O. Gülseren, T. Yildirim, and S. Ciraci,  Phys. Rev. B  67, 165424  (2003).

 3.  “Systematic study of adsorption of single atoms on a carbon  nanotube”,  E. Durgun, S. Dag, V. M. K. Bagci, O. Gülseren, T. Yildirim, and S. Ciraci,  Phys. Rev. B  67, 201401 (R) (2003).

 4.  “High-conducting magnetic nanowires obtained from uniform titanium-covered carbon nanotubes”,  S. Dag, E. Durgun, and S. Ciraci,  Phys. Rev. B  69, 121407   (2004).

 5.    “A comparative study of O₂ adsorbed carbon nanotubes”,  S. Dag, O. Gülseren and S. Ciraci,  Chem. Phys. Lett.  380, Issues 1-2,  1-5  (2003).

 6.  “Electronic structure of the contact between carbon nanotube and metal electrodes”,  S. Dag, O. Gülseren,  S. Ciraci,  T. Yildirim , Appl. Phys. Lett.  83, Issue 15,  3180-3182,   (2003).  (This study highlighted in Nano Today, December 2003. )

 7.   “Functionalized carbon nanotubes and device applications”, S. Ciraci, S Dag, T Yildirim, O Gülseren and R T Senger   J. Phys.:  Condens. Matter    16,   29  R901-R960   (2004).

 8.   “Energetics and Electronic Structures of Individual Atoms Adsorbed on Carbon Nanotubes”,  E. Durgun, S. Dag,  S. Ciraci,  O.  Gulseren,  J. Phys. Chem. B  108(2);  575-582  (2004).

 9.   “Initial stages of Pt growth on Ge(001) studied by scanning  tunneling microscopy and density functional theory”,  Oguzhan Gurlu, Harold J.W. Zandvliet, Bene Poelsema, S. Dag, S. Ciraci,  Phys. Rev. B  70, 085312   (2004).

 10.    “Theoretical study of Ga-based nanowires and the interaction of Ga with single-wall carbon nanotubes”,  E. Durgun, S. Dag, and S. Ciraci,  Phys. Rev. B     70, 155305   (2004).

 11.   “Theoretical study of crossed and parallel carbon nanotube junctions         and  three-dimensional grid structures”,  S. Dag,  R. T. Senger  and S. Ciraci,  Phys. Rev. B  70,  205407,  (2004).

 12.  “Electronic and magnetic properties of zinc blende half-metal superlattices”,  C. Y. Fong  M. C. Quian   J. E. Pask, P. Yang,  S. Dag,   Appl. Phys. Lett. 84 ,  2 ,  239   (2004).

 13.  “Six low-strain zinc-blende half metals: An ab initio investigation”,  J. E. Pask, L. H. Yang, C. Y. Fong, W. E. Pickett, and S. Dag   Phys. Rev. B  67, 224420  (2003).

 14.   “Atomic scale study of superlow friction between hydrogenated diamond surfaces”,  S. Dag and S. Ciraci,  Phys. Rev. B 70, 241401 (R)  (2004).

 15.   “Ab-initio Electron Transport Calculations of Carbon Based String Structures”,   S. Tongay   R.T. Senger   S. Dag   and  S. Ciraci  ,  Phys. Rev. Lett.  93, 136404  (2004).

 16.  “Chiral Single-Wall Gold Nanotubes”,  R.T. Senger,   S. Dag,  and S. Ciraci   Phys. Rev. Lett.  93, 196807  (2004).

 17.   “Coverage and Strain Dependent Magnetization of titanium coated carbon nanotubes”, S. Dag  and S. Ciraci  Phys. Rev. B 71, 165414 (2005).

 18.   “Half-Metallic Properties of  atomic chains  of  carbon-transition metal compounds ”,  S. Dag, S. Tongay,  E. Durgun,  R. T. Senger,  S. Ciraci,  Phys. Rev. B. 72, 155444 (2005).

      19.   “Carbon string and tubular structures: First-principles calculations of structural, electronic and transport properties”,  R. T. Senger, S. Tongay, E. Durgun, S. Dag, and S. Ciraci, Phys. Rev. B  71, 235406 (2005).

 20.    “Atomic and electronic structure of carbon strings”,  S. Tongay, S. Dag, E. Durgun, R. T. Senger, and S. Ciraci,  Jour. Phys: Cond. Matter 17, 3823 (2005).

 21.  “Adsorption and dissociation of hydrogen molecule on carbon    nanotubes”, S. Dag, Y. Ozturk, S. Ciraci, T. Yildirim, Phys. Rev. B 72, 155404 (2005).

22.      “Spin-polarized ballistic transport in a thin superlattice of  zinc blende half-metallic compounds”, M. C. Qian, C. Y. Fong, W. E. Pickett, C. H. Pask, L. H. Yang, and S. Dag, Phys. Rev. B 71, 012414 (2005).

23.      “Physical mechanism of superlow friction between hydrogenated diamond surfaces”,  S. Ciraci, S. Dag,  Tribology Letters (2005).

24.   "Carbon string structures: First-principles calculations of quantum conductance" R. T. Senger, S. Tongay, S. Dag, E. Durgun, and S. Ciraci Phys. Rev. B 71, 235406 (2005).

25.       “Adsorption of hydrogen molecule by transition metal covered carbon nanotubes”, T. Yildirim, S. Dag, S. Ciraci, Phys. Rev. B (to be published).

        26.      “Half-Metallic atom strings”, E. Durgun, S. Dag, T. Yildirim, S. Tongay, R. T. Senger and S. Ciraci, Nature Materials, (In preparation) (to be published).

        27.   “Physisorption of Oxygen Molecule on Carbon Nanotubes”  S. Dag, O. Gulseren, S. Ciraci, T. Yildirim, Nanoengineered Nanofibrous materials, 137-144 (Edited by S. Guceri Springer-Verlag  2004).

28.   “Functionalization of Carbon Nanotubes: Single atom Adsorption”  O. Gulseren, S. Dag, E. Durgun, T. Yildirim, and S. Ciraci,  Nanoengineered Nanofibrous materials, 165-173 (Edited by S. Guceri Springer-Verlag  2004).

        29.  “Theoretical models for nanodevices & nanomagnets based on carbon nanotubes”, S. Ciraci, O. Gulseren, S. Dag, E. Durgun  and T. Yildirim,  Nanoengineered Nanofibrous materials, 183-197 (Edited by S. Guceri Springer-Verlag  2004).

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