Theoretical Study Group
Research group engages a wide spectrum of problems in material science using quantum-chemical simulation methods.
Theoretical research group was created in 2011 to support the experiments are carried out in FSBSI TISNCM. At present time the theoretical group includes:
Ph.D., senior research scientist
Pavel Sorokin (CV)
phone number: +7 (499) 400-62-25 (416)
mobile phone: +7-916-474-66-64
Ph.D., research scientist
Liubov Antipina (CV)
phone number: +7 (499) 400-62-25 (416)
mobile phone: +7-916-746-96-58
Alexander Kvashnin (CV)
phone number: +7 (499) 400-62-25 (416)
mobile phone: +7-915-175-05-40
Yulia Kvashnina (CV)
phone number: +7 (499) 400-62-25 (416)
mobile phone: +7-965-361-64-35
Bachelor, trainee researcher
phone number: +7 (499) 400-62-25 (416)
mobile phone: +7-915-316-01-44
THE MAIN DIRECTIONS OF RESEARCH
The search for new superhard materialsIt is well known that diamond is the hardest crystal among all known materials. Superhard materials are used in various fields: microelectronics, engineering works, for sharpening clean surfaces for optical components, memory disks, drums for copy machines, for mechanical treatment of various solid metals, alloys and etc. Currently, the diamond anvils are used for the achieving ultrahigh pressure. Applying of new stronger and harder materials leads to increasing the opportunity of experiments to create ultrahigh pressures and synthesize new high pressure phases, to expand scientific knowledge, techniques and technologies.
However, there are a number of cases where the application of diamond is impossible or undesirable. For example, diamond can react with treated material at high temperature. Also diamond is rather expensive material.
The search of new carbon materials which are stronger and harder than diamond is one of the most prospective developing areas of modern materials science. On the other hand, producing of a material with good hardness characteristics is important not only from a practical point of view but also for understanding the connection between the microscopic characteristics of the interatomic interactions and macroscopic properties of matter.
In recent investigation  of theoretical group a number of new superhard carbon phases with elastic modules compared to diamond was predicted. Proposed allotropes are superhard semiconductors with band gap width less than 1.3 eV and with the carrier mobility in several times larger than diamond has which makes these materials prospective for applications in electronics. Atomic structure of such phases is shown at Figure 1.
Second branch of investigations is related with amorphous materials based on polymerized fullerene molecules. The beginning of such investigations has been made by the number of experimental results obtained in FSBI TISNCM [DOI: 10.1016/S0925-9635(97)00232-X, DOI: 10.1016/0375-9601(96)00483-5], where a new superhard phase based on the fullerene C60 with hardness up to 310 GPa which is much higher than the diamond hardness (137 GPa) called tisnumit was reported [DOI: 10.1007/978-94-010-9598-3_19]. This material was obtained at pressures and temperatures above than 13 GPa and 2100 K. A model of an amorphous nanocomposite based on polymerized fullerene was proposed by theoretical group which is shown at Figure 2.
Despite of the monocrystalline materials with outstanding elastic moduli the polycrystal materials may also have the great values of hardness and bulk moduli. At the moment the dependence of the hardness on the crystallite size was obtained for the diamond polycrystals [DOI: 10.1038/421599b] and CBN [DOI: 10.1002/adma.201104361]. One of the proposed theories suggests that the augmentation of the mechanical characteristics is caused by the boundary between crystallites. Two phases of such material (boundary and crystal) change their own mechanical properties according to the crystallite size. Theoretical group is studying diamond polycrystals to explain and confirm the above theory.
The investigations of diamond based nanostructures
Using ab initio (first-principles) methods of calculations the ultrathin diamond films with nanometer thickness, called as diamane were investigated. The chemically induced phase transition in diamanes was studied , according which the multilayered graphene can be transformed into diamond film only through the chemical adsorption of adatoms onto the surface (hydrogen, fluorine, etc.). Theoretical group investigated the stability of diamanes and the phase diagram of such transition for the films with different thickness and different types of the surface was obtained. Figure 4 shows the dependence of the phase transition pressure on the film thickness for diamanes with both clean and hydrogenated surfaces. Popular scientific explanation of this work can be found in the number of web resources including Lenta.ru.
The chemically induced phased transition allows the fabrication of the carbon films not only with diamond crystal structure but also with lonsdaleite structure. The hardness of lonsdaleite (hexagonal diamond) is much higher than hardness of diamond, but, unfortunately, lonsdaleite has not been yet experimentally obtained as a freestanding monocrystal. Thus, chemically induced phase transition offers the opportunities of the experimental fabrication of lonsdaleite monocrystal films. Theoretical group studied the mechanical, electronic and transport properties of nanometer thick lonsdaleite films, and the phase diagram of the transition from multilayered graphene to lonsdaleite film was obtained which determines the main conditions (temperature and pressure) for experimental fabrication of such films.
The study of the properties of prospective nanomaterials in a field of hydrogen energeticsLack of the efficient hydrogen storage materials is one of the major problems toward the successful use of hydrogen as a green alternative fuel for vehicles. The US Department of Energy has set the hydrogen gravimetric capacity target of 6.5 wt% in the perspective materials for industrial usage. Because of its light weight and large surface area, carbon-based nanostructures are considered as most promising materials for the hydrogen storage. Carbon nanostructures decorated by transition and alkali metal atoms have shown high potential for hydrogen storage materials which was confirmed by number of theoretical and experimental studies. We have shown that such carbon materials as carbyne and graphane with bonded metal atoms (Figure 5) could be used as prospective material for hydrogen storage.
Figure 5. A – carbyne with adsorbed atoms of calcium, B – graphane with adsorbed atoms of alkali metals
The research methods used in our group are included different theoretical approaches: ab initio, semiempirical methods and classical potentials.
The electronic and mechanical properties of all investigated structures are determined using methods of density functional theory (DFT) implemented in such software packages as VASP, QuantumEspresso, SIESTA which allows to estimate a wide range of properties (mechanical, electronic, optical) of bulk and nanoscale materials. Also DFT method is widely used for calculation of phase diagrams (Figure 6). Using this method it is possible to estimate the values of phase transition pressure with good accuracy in a wide temperature range and allows to study the metastable phases which are not always easy to obtain in experiments.
Figure 6. Phase diagram for graphite-diamond transition obtained in experiment in comparison with simulation
Classical molecular dynamics method with empirical interatomic potentials implemented in such software packages as LAMMPS and GULP are used in our group. The main advantage of this approach is possibility to investigate materials consisted of hundreds and thousands of atoms with sufficient accuracy.
All calculations of simulation of carbon material properties are carrying out using high performance computing cluster T-Platforms based on T-Blade 1.1.
2014Articles in scientific journals:
- L.A. Chernozatonskii, P.B. Sorokin, A.A. Artyukh, Novel graphene-based nanostructures: physicochemical properties and applications // Russian Chemical Reviews 2014. V.83, N3. pp.251-279 (download pdf).
- Kvashnin A.G., Sorokin P.B., Lonsdaleite films with nanometer thickness // J. Phys. Chem. Lett. V.5, P. 541-548 (2014) (DOI: 10.1021/jz402528q, download pdf). see also: LiveSlides
- Kvashnin A.G., Chernozatonskii L.A., Yakobson B.I., Sorokin P.B. Phase diagram of quasi-two-dimensional carbon // Nano Letters 2014. V.14, P.676-681 (DOI: 10.1021/nl403938g, download pdf). see also: Lenta.ru, phys.org
- Tang D.M., Kvashnin D.G., Najmaei S., Bando Y., Kimoto K., Koskinen P., Ajayan P., Yakobson B., Sorokin P., Lou J., Golberg D., Nanomechanical cleavage of molybdenum disulphide atomic layers // Nature Communication 2014. V.5, P.3631 (DOI: 10.1038/ncomms4631, download pdf)
- Sorokin P.B., Kvashnin A.G., Zhu Z., Tománek D. // Spontaneous graphitization of ultrathin cubic structures: A computational study (submitted)
- S. Entani, P.B. Sorokin, P.V. Avramov, M. Ohtomo, Y. Matsumoto, L.Yu. Antipina, N. Hirao, I. Shimoyama, H. Naramoto, Y. Baba and S. Sakai // Sapphire Heterostructure: Contracted Interlayer Distance and Hole-Doping through Electrostatic Interactions (submitted)
- L.Yu. Antipina, P.B. Sorokin, D. Tománek // Are diamond nanoparticles harder than diamond? (submitted).
2013Articles in scientific journals:
- P. B. Sorokin, L.A. Chernozatonskii. Semiconducting nanostructures based on graphene, Phys. Usp. 56, 105–122 (2013). (DOI: 10.3367/UFNe.0183.201302a.0113, download pdf)
- Seiji Sakai, Yoshihiro Matsumoto, Manabu Ohtomo, Shiro Entani, Pavel V Avramov, Pavel B Sorokin, Hiroshi Naramoto, High spin polarization at the Fe/C60 interface in the Fe-doped C60 film, Synthetic Metals 173 , 22-25 (2013) (DOI: 10.1016/j.synthmet.2012.10.027, download pdf)
- D.G. Kvashnin, P.B. Sorokin, J.W. Brüning and L.A. Chernozatonskii, The impact of edges and dopants on the work function of graphene nanostructures. The way to high electronic emission from pure carbon medium, Appl. Phys. Lett. 102, 18, pp. 183112(5) (2013) (DOI: 10.1063/1.4804375, download pdf)
- Yu.A. Kvashnina, A.G. Kvashnin, P.B. Sorokin, Investigation of new superhard carbon allotropes with promising electronic properties, J. Appl. Phys. 114, 183708(5) (2013) (DOI: 10.1063/1.4829002, download pdf)
Participations in conferences:
- D. G. Kvashnin, P. B. Sorokin, L. A. Chernozatonskii, Theoretical study of changes of the work function of graphene nanostructures. The way to high electronic emission from pure carbon medium, book of abstracts of Physics Boat 2013 "Atomic structure of nanosystems from first-principles simu lations and microscopy experiments", Helsinki (Finland) - Stokholm (Sweden), June 4-6 2013, p. 62.
- P. B. Sorokin, D. G. Kvashnin, L. Yu. Antipina, D. V. Golberg, Theoretical aspects of unzipping of WS2 nanotubes, book of abstracts of Physics Boat 2013 "Atomic structure of nanosystems from first-principles simulations and micros-copy experiments", Helsinki (Finland) - Stokholm (Sweden), June 4-6 2013, p. 69.
- Yu.A. Kvashnina, A.G. Kvashnin, I.V. Dudenkov, L.Yu. Antipina, P.B. Sorokin, Prediction of new superhard carbon allotropes, Abstracts of Joint International Conference “Advanced Carbon NanoStructures”, St Petersburg, Russia, 1 – 5 July 2013 p. 221
- D. G. Kvashnin, P. B. Sorokin, L. A. Chernozatonskii, Investigation of the strong influence of the edges and dopants to the work function of graphene-based nanostructures, Book of abstracts of International Conference Advanced Carbon Nanostructures (ACNS'2013), St. Petersburg, Russia, July 01-05, 2013. p. - 80.
- A.G. Kvashnin, L.A. Chernozatonskii, P. B. Sorokin, Diamond films with nanometer thickness: New 2D carbon based nanomaterial, Novel 2D materials: tuning electronic properties on the atomic scale, Bremen, Germany, June 11-14, 2013. p. P28
- D. G. Kvashnin, P. B. Sorokin, L. Yu. Antipina, D. Golberg, Theoretical explanation of unzipping process of WS2 nanotubes, Abstracts of Symposium F, E-MRS Fall Meeting, Warsaw, Poland,16-20 September 2013, Nano and Advanced Materials Workshop and Fair (NAMF 2013), Satellite of E-MRS Fall Meeting, Warsaw, Poland, 16-19 September 2013
- A.G. Kvashnin, L.A. Chernozatonskii, B.I. Yakobson, P.B. Sorokin. Investigation of properties of diamond films with nanometer thickness, Abstracts of Symposium F, E-MRS Fall Meeting, Warsaw, Poland,16-20 September 2013, Nano and Advanced Materials Workshop and Fair (NAMF 2013), Satellite of E- MRS Fall Meeting, Warsaw, Poland, 16-19 September 2013
- D.G. Kvashnin, P.B. Sorokin, L.Yu. Antipina, D.V. Golberg, L.A. Chernozatonskii, The explanation of the unzipping process of WS2 nanotubes by theoretical methods, Proceedings of XVI Annual International Youth Conference "Biochemical Physics" IBCP RAS, Moscow, Russia, October 28-30 2013.
- Yu.A. Kvashnina, A.G. Kvashnin, I.V. Dudenkov, L.Yu. Antipina, T.P. Sorokina, P.B. Sorkin, New carbon allotropes: mechanical and electronic properties, Zelenograd, October 2-3 2013, p. – 71
- L.Yu. Antipina , S. Entani, P.B. Sorokin, P.V. Avramov, M. Ohtomo, Y. Matsumoto, H. Naramoto, S. Sakai. “Unexpected strong interaction at the single-layer graphene/α-Al2O3(0001) interface” // Atomic structure of nanosystems from first -principles simulations and microscopy experiments, Physics Boat Workshops, Helsinki, Finland - Stockholm, Sweden, 4-6 June 2013.
- L.Yu. Antipina , P.B. Sorokin. “The high hydrogen adsorption rate material based on graphane decorated with alkali metals” // Novel 2D materials: Tuning electronic properties on the atomic scale, CECAM workshop, Bremen, Germany, 10-14 June 2013
- P.B. Sorokin, Diamond films with nanometer thickness: synthesys, characteristics, applications, Report at the seminar in FSBI TISNCM(download pdf)
- Sorokin P.B. Theoretical investigation of Diamond films with nanometer thickness, Report at the Technological Institute of Dresden (Germany) (download pdf)
2012Articles in scientific journals:
- Chernozatonskii L.A., Mavrin B.N., Sorokin P.B., Determination of ultrathin diamond films by Raman spectroscopy // Physica Status Solidi B 2012. V.8. P. 1550-1554 (DOI: 10.1002/pssb.201147478, download pdf).
- Determination of ultrathin diamond films by Raman spectroscopy / L.A. Chernozatonskii, B.N. Mavrin and P.B. Sorokin // Physica Status Solidi B – 2012 (в печати, DOI: 10.1103/PhysRevB.86.085435, download pdf).
- Chernozatonskii L.A., Kvashnin D.G., Sorokin P.B., Kvashnin A.G., Brüning J.W. Strong, Influence of Graphane Island Configurations on the Electronic Properties of a Mixed Graphene/Graphane Superlattice // J. Phys. Chem. C 2012. V.116, №37. P. 20035-20039 (DOI: 10.1021/jp304596y, download pdf).
- Avramov P.V., Fedorov D.G., Sorokin P.B., Sakai S., Entani S., Ohtomo M., Matsumoto Y., Naramoto H. Intrinsic Edge Asymmetry in Narrow Zigzag Hexagonal Heteroatomic Nanoribbons Causes their Subtle Uniform Curvature // J. Phys. Chem. Lett. 2012. V.3. P. 2003-2008 (DOI: 10.1021/jz300625t, download pdf).
Participations in conferences:
- Kvashnin A. G., Sorokin P. B., Chernozatonskii L. A., Ultrathin diamond nanofilms as possible two-dimensional insulator: electronic and elastic properties, Abstracts of International conference “Towards Reality in Nanoscale Materials V” (TRNM V), Levi, Lapland, Finland, 20-22 February 2012, p. – 72.
- Filicheva Yu. A., Kvashnin A. G., Sorokin P. B., Theoretical investigation of the diamond films with implanted oxygen atoms, Abstracts of International conference “Towards Reality in Nanoscale Materials V” (TRNM V), Levi, Lapland, Finland, 20-22 February 2012, p. – 62.
- Yu. A. Filicheva, L. Yu. Antipina, A. G. Kvashnin, P. B. Sorokin, New superhard carbon modifications: structure and properties, Conference proceeding and abstracts of eighteenth Russia scientific conference of physicist and young scientists, Krasnoyarsk, Russia, 29 March – 5 April 2012, p.-641.
- Filicheva Yu. A., Kvashnin A.G., Antipina L. Yu., Sorokin P. B., «New superhard carbon allotropes: elastic and electronic properties». The IV International Seminar on Nanosciences and Nanotechnologies, Ciudad de la Habana, Cuba, 17-19 September 2012.
- Kvashnin A. G., Sorokin P. B., Chernozatonskii L.A., Particularities of phase transitions in ultrathin diamond films: theoretical study, Proceedings of XII Annual International Youth Conference "Biochemical Physics" IBCP RAS, Moscow, Russia, 29-31 October 2012.
- A. G. Kvashnin, L. A. Chernozatonskii, T. P. Sorokina, P. B. Sorokin, Theoretical investigation of the properties of ultrathin diamond films, Proceedings of the Eighth International Conference on Carbon: fundamental problems of science, materials science, technology, Moscow, Troitsk, Russia, 25 - 28 September 2012.
- Yu. A. Filicheva, A. G. Kvashnin, T. P. Sorokina, P. B. Sorokin, Structure and properties of new carbon allotropes, Proceedings of the Eighth International Conference on Carbon: fundamental problems of science, material science, technology, Moscow, Troitsk, Russia, 25 – 28 September 2012, p.-533.
2011Articles in scientific journals:
- Sorokin P. B., Singh A. K., Lee H., Antipina L. Yu. and Yakobson B.I. Calcium-Decorated Carbyne Networks as Hydrogen Storage Media // Nano Lett. – 2011. – V.11, №7. – PP: 2660–2665 (DOI: 10.1021/nl200721v, download pdf). See also on the topic: phys.org/news/2011-06-carbon-grapevine-hydrogen.html.
- Chernozatonskii L. A., Sorokin P. B., Kuzubov A. A., Sorokin B. P., Kvashnin A. G., Kvasnin D. G. and Yakobson B. I. Influence of Size Effect on the Electronic and Elastic Properties of Diamond Films with Nanometer Thickness // J. Phys. Chem. C – 2011. – V.115, №1. – P.132-136, (DOI: 10.1103/PhysRevB.86.085435, download pdf).
Participation in conferences:
- Sorokin P. B., Chernozatonskii L. A., Avramov P. V., Kvashnin A. G., Electronic and elastic properties of diamond films with nanometer thickness, Book of abstracts International conference “Advanced carbon nanostructures”, St Petersburg, Russia, July 4-8, 2011, p. – 182.
- Chernozatonskii L. A., Artyukhov B. I., Biro L., Mark. G., Sorokin P. B., Kvashnin A. G., Kvashnin D. G., Yakobson B.I., Nanostructures based on H- (or F-) atom functionalized graphene elements for electronic and optic nanoengineering, Book of abstracts International conference “Advanced carbon nanostructures”, St Petersburg, Russia, July 4-8, 2011, p. – 26.
- Ribas M. A., Singh A. K., Sorokin P. B., Yakobson B. I. Nanoroads and Quantum Dots on Fluorinated Graphene Abstracts of Joint International Conference, Book of abstracts International conference “Advanced carbon nanostructures”, St Petersburg, Russia, July 4-8, 2011, p. – 105.
- Kvashnin A. G., Sorokin P.B., Investigation of the features of phase transitions in ultrathin diamonds, Abstracts of the conference of young scientists of the Ural region with international participation, Perm, Russia, October 6-7, 2011, p. – 144.