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1

Ab initio study of GdCo5 magnetic and magneto-optical properties

Mahdi M., Djabri A., Koc M. M., Boukhalfa R., Erkovan M., Chumakov Yu., Chemam F.

Materials Science Poland

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2019

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Vol. 37, No. 2

182--189

EN

The full potential linearized augmented plane wave method (FLAPW) including the spin-orbit coupling has been used to study the structural, electronic and magnetic properties of GdCo5 compound. The calculations were performed within the local spin density approximation (LSDA) as well as Coulomb corrected LSDA + U approach. The study revealed that the LSDA + U method gave a better representation of the band structure, density of states and magnetic moments than LSDA. It was found that the spin magnetic moment of Co (2c) and Co (3g) atoms in the studied compound is smaller compared to the one in bulk Co. The optical and magneto-optical properties and the magneto-optical Kerr effect have also been investigated.

2

Thermal conductivity of silicon doped by phosphorus: ab initio study

Andriyevsky B., Janke W., Stadnyk V. Y., Romanyuk M. O.

Materials Science Poland

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2017

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Vol. 35, No. 4

717--724

EN

An original approach to the theoretical calculations of the heat conductivity of crystals based on the first principles molecular dynamics has been proposed. The proposed approach exploits the kinetic theory of phonon heat conductivity and permits calculating several material properties at certain temperature: specific heat, elastic constant, acoustic velocity, mean phonon scattering time and coefficient of thermal conductivity. The method has been applied to silicon and phosphorus doped silicon crystals and the obtained results have been found to be in satisfactory agreement with corresponding experimental data. The proposed computation technique may be applied to the calculations of heat conductivity of pure and doped semiconductors and isolators.

3

Structural stability, electronic structure and magnetic properties of the new hypothetical half-metallic ferromagnetic full-Heusler alloy CoNiMnSi

Elahmar M. H., Rached H., Rached D., Benalia S., Khenata R., Biskri Z. E., Bin Omran S.

Materials Science Poland

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2016

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Vol. 34, No. 1

85--93

EN

We investigated the structural stability as well as the mechanical, electronic and magnetic properties of the Full-Heusler alloy CoNiMnSi using the full-potential linearized augmented plane wave (FP-LAPW) method. Two generalized gradient approximations (GGA and GGA + U) were used to treat the exchange-correlation energy functional. The ground state properties of CoNiMnSi including the lattice parameter and bulk modulus were calculated. The elastic constants (C-ij) and their related elastic moduli as well as the thermodynamic properties for CoNiMnSi have been calculated for the first time. The existence of half-metallic ferromagnetism (HM-FM) in this material is apparent from its band structure. Our results classify CoNiMnSi as a new HM-FM material with high spin polarization suitable for spintronic applications.

4

Structural properties of hypothetical CeBa2Cu3O7 compound from LSDA+DMFT calculations

Łuszczek M.

Materials Science Poland

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2016

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Vol. 34, No. 3

617--626

EN

The hypothetical stoichiometric CeBa2Cu3O7 (Ce123) compound, which has not been synthesized as a single phase yet, was studied by the density functional theory (DFT). We utilized a method which merges the local spin density approximation (LSDA) with the dynamical mean-field theory (DMFT) to account for the electronic correlations. The LSDA+DMFT calculations were performed in the high-temperature range. The particular emphasis was put on the pressure-induced changes in the electronic band structure related to strongly correlated 4f states. The computational results indicate the occurrence of a large negative volumetric thermal expansion coefficient near T = 500 K and a trace of a low-volume isostructural metastable state at high temperatures.

5

Ab initio calculations of structural, elastic, electronic and thermodynamic properties of the cerium filled skutterudite CeRu4P12 under the effect of pressure

Berrahal M., Ameri M., Al-Douri Y., Hashim U., Varshney D., Ameri I., Boubchir M., Abderrahim B.

Materials Science Poland

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2015

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Vol. 33, No. 4

699--708

EN

The paper presents an investigation on crystalline, elastic and electronic structure in addition to the thermodynamic properties for a CeRu4P12 filled skutterudite device by using the full-potential linear muffin-tin orbital (FP-LMTO) method within the generalized gradient approximations (GGA) in the frame of density functional theory (DFT). For this purpose, the structural properties, such as the equilibrium lattice parameter, bulk modulus and pressure derivatives of the bulk modulus, were computed. By using the total energy variation as a function of strain we have determined the independent elastic constants and their pressure dependence. Additionally, the effect of pressure P and temperature T on the lattice parameters, bulk modulus, thermal expansion coefficient, Debye temperature and the heat capacity for CeRu4P12 compound were investigated taking into consideration the quasi-harmonic Debye model.

6

The B-Li System. Calorimetric and Theoretical Studies

Dębski A., Braga M. H., Gąsior W.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 4

2513--2520

EN

The standard enthalpy of formation of the B78Li22 alloy was measured with the use of the water reaction calorimetric method at 25 °C (298 K). An X-ray diffraction study of the prepared sample was conducted. The obtained diffraction pattern was different from the patterns for the B3Li and B14Li3 phases. The standard enthalpy of formation obtained for the B78Li22 alloy was -39.0 ± 0.7 kJ/mole of atoms. This value corresponds well with the formation enthalpies of the phases from the boron-lithium system. Theoretical calculations of the standard enthalpy of formation were conducted for the B78Li22 alloy and the phases from B-Li system, which were investigated earlier. A discussion of the deviations observed between both sets of data (experimental and calculated) was performed. Additionally, DTA studies were performed for 14 alloys of the concentrations from 40 to 100 at. % of Li.

PL

Standardowa entalpia tworzenia stopu B78Li22 została zmierzona metodą kalorymetrii reakcyjnej wodnej. Próbka stopu po wyżarzaniu była poddana badaniom strukturalnym metodą dyfrakcji promieniowania rentgenowskiego. Uzyskany dyfraktogram jest inny od dyfraktogramów dla faz B3Li ora B14Li3. Zmierzona standardowa entalpia tworzenia stopu B78Li22 wyniosła -39.0 ± 0.7 kJ/mol atomów. Wartość ta dobrze koreluje z entalpią tworzenia faz z układu bor-lit. Przeprowadzone zostały również obliczenia teoretyczne standardowej entalpii tworzenia dla stopu B78Li22 oraz faz z układu B-Li, wcześniej badanych. Zaobserwowane rozbieżności między teoretycznymi i eksperymentalnymi wartościami entalpii tworzenia zostały przedyskutowane. Ponadto, wykonano pomiary DTA dla 14 stopów o stężeniach od 40 do 100 % at. Li.

7

First-principles investigation of the structural stability and electronic properties of Pd doped monoclinic Cu6Sn5 intermetallic compounds

Shao W Q, Lu W C, Chen S O

Materials Science Poland

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2014

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Vol. 32, No. 4

592--596

EN

Tri-layer Au/Pd/Ni(P) films have been widely used as surface finish over the Cu pads in high-end packaging applications. It was found that a thin (Cu,Pd)6Sn5 IMC layer was beneficial in effective reducing inter-diffusion between a Cu substrate and a solder, and therefore the growth of the IMC layer and the EM (electromigration) processes. In this study, the structural properties and phase stability of monoclinic Cu6Sn5-based structures with Pd substitutions were studied by using the firstprinciples method. The (Cu,Pd)6Sn5 structure with the 4e site substituted by Pd has the lowest heat of formation and is the most stable among (Cu,Pd)6Sn5 structures. Hybridization of Pd-d and Sn-p states is a dominant factor for stability improvement. Moreover, Pd atoms concentration corresponding to the most stable structure of (Cu,Pd)6Sn5 was found to be 1.69 %, which is consistent with the experimental results.

8

Potential Energy Surface (PES) scan of gas-phase L-proline

El Guerdaoui A., El Kahoui Y., Bourjila M., Tijar R., El Gridani A.

International Letters of Chemistry, Physics and Astronomy

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2014

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Vol. 19, iss. 1

26--34

EN

We performed here a systematic ab initio calculations on neutral gas-phase L-proline. A total of 8 local minima were located by geometry optimization of the trial structures using density functional theory (DFT) with B3LYP three parameter hybrid potential coupled with the 6-31G)d( basis set. The absolute minimum obtained will be subject to a rigid potential energy surface (PES) scan by rotating its carboxylic group using the same method with more accurate basis set B3LYP/6-311++G(d,p), to get a deeper idea about its conformational stability. The main aim of the present work was the study of the rigidity of the L-proline structure and the puckering of its pyrrolidine ring.

9

Obliczenia z pierwszych zasad własności defektów rodzimych w ZnRh2O4

Volnianska O., Bogusławski P.

Elektronika : konstrukcje, technologie, zastosowania

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2014

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Vol. 55, nr 9

27-29

PL

W pracy przedstawiono wyniki obliczeń dotyczących struktury elektronowej i równowagowych koncentracji punktowych defektów rodzimych (luki, atomy międzywęzłowe, defekty antystrukturalne) w ZnRh2O4. Obliczenia wykonane w przybliżeniu lokalnej gęstości uwzględniły poprawki +U typu Hubbarda, co prowadzi do dobrej wartości przerwy wzbronionej. Dominującymi defektami są luka cynkowa i jon Zn podstawiający Rh. Oba defekty są płytkimi akceptorami o energii tworzenia poniżej 1 eV, co może tłumaczyć obserwowane doświadczalnie w ZnRh2O4 przewodnictwo typu p.

EN

Energy levels and formation energies of native point defects, i.e., vacancies, interstitials, and cation antisites, in ZnRh2O4 were analyzed within DFT-GGA calculations with +U on-site correction imposed on both 4d(Rh) and 2p(O) states. There are two dominant defects, the VZn vacancy and the ZnRh antisite, which are characterized by low formation energies, in the O-rich and Zn-rich conditions, respectively. Both defects are shallow acceptors, and they can be responsible for the observed p-type conductivity of ZnRh2O4.

10

New Medium - Size Basis Sets for Rare - Gas Atoms

Makarewicz J.

Computational Methods in Science and Technology

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2012

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Vol. 18, No. 2

XX-XX

EN

New medium-size basis sets are constructed for rare-gas (Rg) atoms and tested on their dimers Rg2. The main part of the these bases contains the standard aug-cc-pVTZ basis set modified and extended by the g- and h-polarization functions. Their optimization allows accurate calculations of the dispersion interaction without the involvement of the bond functions. A new convenient analytical potential function is invented to fit accurately the interaction energy. The potentials derived for Rg dimers predict the vibrational transition energies and rotational constants to accuracy of 1%.

11

Tautomeric Equilibria in Solutions of 1-Phenacylpyridazin-1-ium and 1-(o-Fluorophenacyl)pyridin-1-ium Cations. DFT and NMR Studies

Gawinecki R., Dobosz R., Ośmiałowski B., Zakrzewska A.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 9

1623-1628

EN

Although 1-(2-oxo-2-phenylethyl)pyridazin-1-ium and 1-[2-oxo-2-(o- fluoro phenyl - ethyl)]pyridin-1-ium cations may equilibriate with the respective enol and enaminone tautomeric forms, both experimental NMR data and results of ab in itio calculations show the keto forms to be the only species present in DMSO solution. Intramolecular hydrogen bonds and pi electron delocalization seem to have negligible effect on stabilization of the tautomers. On the other hand, electrostatic repulsions between the onium nitrogen and hydroxy oxygen atoms in the compounds studied are considered to be responsible for the in stability of the enol and enaminone tautomeric forms.

12

Infrared Matrix Isolation and Theoretical Study of Methylglyoxal

Mucha M., Sałdyka M., Mielke Z.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 5

943-956

EN

Methylglyoxal (MG) was studied by matrix-isolation IR spectroscopy supported by MP2/6-311++G(2d,2p) calculations. The experimental results show that the molecule exists in the trans conformation (Cs symmetry). The trans-MG isomer is estimated to lie 4.96 kcal/mol be low the cis-MG isomer and the rotational barrier is 5.48 kcal/mol on the ground-state path way from trans- to cis-MG. The spectra evidence formation of weak molecular MGźźźN2 complexes when the argon matrix is doped both with MG and N2.

13

Mechanical and electronical properties of ZnS under pressure

Bilge M., Özdemir Kart S., Kart H. H., Cagin T.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 31, nr 1

29-34

EN

Purpose: The wide-gap semiconductor materials are very important for application in the fields of optical device technology. ZnS is wide-gap semiconductor that is attractive material due to the polymorphic structural transformation and it is suitable semiconductor for applications in infrared optics, ultraviolet laser devices, electronic image display, high-density optical memory, solar cell etc. The goal is to evaluate mechanical and electrical properties of ZnS dunder pressure. Design/methodology/approach: We report ab-initio calculations of lattice constants, bulk modulus and elastic constants of the B1 (rocksalt), B3 (zincblende) and B4 (wurtzite) structures of ZnS. Ab-initio calculations are based on the density functional theory (DFT) within generalized gradient approximation (GGA) for the exchange-correlation potential. Findings: Phase transition pressures from B4 phase to B3 phase, from B3 phase to B1 phase and from B4 phase to B1 are predicted from intersection of the enthalpy-pressure data for the three phases. These results are consistent with the experimental and other theoretical calculations. Mechanical properties of ZnS under high pressure are also calculated. It is seen that the mechanical properties of ZnS under high pressure are quite different from those ambient condition. The band structure, density of states (DOS) and energy gaps are also given for B3 structure of ZnS. Research limitations/implications: The results are compared with the previous theoretical and experimental data. Originality/value: Evaluation of mechanic and electronical properties of ZnS under pressure.

14

Quantum mechanical calculations of elastic properties of doped tetragonal yttria-stabilized zirconium dioxide

Natanzon Y., Łodziana Z.

Computer Science

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2008

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Vol. 9

87-96

EN

We report first principles calculations of the electronic and elastic properties of yttria-stabilized tetragonal zirconium dioxide doped with metal oxides like: GeO2, TiO2, SiO2, MgO and Al2O3. It is shown that addition of such dopants affects selected elastic properties of ZrO2, which is driven by the attraction of electron density by dopant atom and creation of stronger dopant-oxygen bonds. This effect contributes to the increase of superplasticity of doped material.

PL

W pracy przedstawione są wyniki kwantowo-mechanicznych obliczeń własności elektronowych i elastycznych fazy tetragonalnej dwutlenku cyrkonu stabilizowanego tlenkiem itru z domieszkami tlenków metali, takich jak GeO2, TiO2, SiO2, MgO oraz Al2O3. Pokazano, że domieszkowanie wpływa na wybrane stałe elastyczne ZrO2, co jest spowodowane zmianami rozkładu gęstości elektronowej w pobliżu atomu domieszki oraz kreacją silniejszego wiązania domieszka-tlen. Ten efekt wnosi wkład do zwiększenia nadplastyczności domieszkowanego materiału.

15

Synthesis, Characterization and ab initio Calculations on 1-Phenyl-3-p-fluorophenyl-5-p-methoxyphenyl-2-pyrazoline

Zhao P. S., Li Y. F., Guo H. M., Wang X., Jian F. F.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 10

1735-1735

EN

1-Phenyl-3-p-fluorophenyl-5-p-methoxyphenyl-2-pyrazoline has been synthesized and characterized by elemental analysis, IR, UV-Vis and X-ray single crystal diffraction. Ab initio calculations for the title compound have been carried out and the calculated results show that HF/6-311G** method can well reproduce the structural parameters. The theoretical electronic absorption spectra have been predicted by using 6-311G** and 6-311++G** basis sets and compared with the experimental values, indicating that HF-CIS method can well predict electronic absorption spectra for the system studied here. On the basis of vibrational analyses, the thermodynamic properties of the title compound at different temperatures have been calculated, revealing the correlations between C 0 p,m , S 0 m , H 0 m and temperature.

16

Structural Studies of 1-Aryl-2-aminoimidazolinium Bromides: Focus on Tautomer Preference of the 2-Aminoimidazoline Moiety in the Solid State

Dobrowolski M., Cyrański M., Pisklak M., Wawer I., Matosiuk D.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 5-6

1037-1048

EN

The crystal structures of five 1-(4-X-phenyl)-2-aminoimidazolinium bromides (where X = -OCH3, -CH3, -H, -Cl and -NO2) were determined by X-ray crystallography with the aim to investigate the tautomer preference of the aminoimidazoline moiety in the solid state. The molecular structures clearly indicate that only the ring nitrogen is protonated. The crystals are stabilized by interactions between the hydrogens of the amino group (also NH fragment of the imidazoline ring) and bromide anion. In the case of the nitro derivative additional strong hydrogen bonds are a consequence of the presence of water molecule in the crystal lattice. The methoxy and nitro derivatives were studied by 15N CP/MAS NMR and the analysis of the tautomer preference was completed by ab initio calculations at the B3LYP/6-311+G** level.

17

Lithium-7 NMR and ab initio Calculation Studies of Complexation of Li+ Ion with 12-Crown-4, Benzo-12-crown-4, 15-Crown-5, Benzo-15-crown-5, and Dibenzo-15-crown-5 in Binary Nitromethane-Acetonitrile Mixtures

Shamsipur M., Alizadeh N., Rofouei M. K., Alizadeh K.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 10

1743-1743

EN

Complexes of 12-crown-4 (12C4), benzo-12-crown-4 (B12C4), 15-crown-5 (15C5), benzo-15-crown-5 (B15C5) and dibenzo-15-crown-5 (DB15C5) with Li+ ion were investigated by lithium-7 NMR in a number of nitromethane (NM)-acetonitrile (AN) binary mixtures. In all cases, the exchange between the free and complexed lithium ionwas fast on the NMR time scale and a single population average resonance was observed. Both 1:1 and 2:1 (sandwich) complexeswere observed between lithium ion and 12C4 and B12C4 in pure nitromethane solution. Stepwise formation constants of the 1:1 and 1:2 (metal/ligand) complexes were evaluated from computer fitting of the NMR mole ratio data to equations which relate the observed metal ion chemical shifts to formation constants. There is an inverse linear relationship between the logarithms of the stability constants and the mole fraction of acetonitrile in the solvent mixtures. The stability of the complexes varies inversely with the Gutmann donor number of the solvent. The stability order of the complexes was found to be 15C5.Li+> B15C5.Li+> DB15C5.Li+> 12C4.Li+ > B12C4.Li+. The optimized structures of the free ligands and their 1:1 and 2:1 complexes with Li+ ionwere predicted by ab initio theoretical calculations using theGaussian 98 software, and the results are discussed.

18

Theoretical Study on the Chemical Reactions in the Cl-ClO Catalytic Cycle

Bing D., Mao L., Zhao Y., Li X., Hao F., Liu F.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 11

1857-1864

EN

One of the processes of ozone depletion in the polar stratosphere was investigated using ab initio calculations at the MP2, B3LYP, QCISD(T), G2, G2MP2 and CBS-Q levels. The reactional energy, the enthalpy of formation, and the relativeGibbs free energy of the reactions in the Cl-ClO catalytic cycle were calculated. The energies of the transition states of the reactions were calculated, followed by the calculations of the reaction barriers. The results support the mechanism of ozone deleption by the Cl-ClO catalytic cycle, and explain the basic reason of ozone depletion from the point of energy.

19

NMR Properties of the Formic Acid Dimer

Jaroniec J., Jaszunski M.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 7

1061-1074

EN

NMR properties - nuclear quadrupole coupling constants, shielding constants and indirect spin-spin coupling constants - in the formic acid dimer are studied using ab initio methods. The accuracy of the calculations is examined for the C2hminimum structure of (HCOOH)2, comparing theMCSCF (multi-configuration SCF) and CCSD (coupled cluster singles and doubles) results. The dependence of the NMR parameters on dimer geometry is analysed for simultaneous double proton transfer, considering the C2h minimum, theD2h transition state and a few intermediate structures, aswell as for two structures representing single proton transfer. For the nuclei involved in the hydrogen bonds not only the effects of the dimerization are very large; the computed NMR parameters also vary significantly with the structure of the cyclic formic acid dimer.

20

Keto_Enol Tautomerism in Pyruvic Acid-Theoretical (HF, MP2 and DTF in the Vacuo) Studies

Raczyńska E., Duczmal K., Darowska M.

Polish Journal of Chemistry

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2005

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Vol. 79 / nr 4

689-697

EN

Extended quantum-chemical calculations {HF, MP2, DFT(B3LYP) in vacuo} were performed for neutral pyruvic acid and its enol forms. Among various tautomers-rotamers considered, three keto (Tce, Tte and Cte) and six enol structures (E1-E6) are found to be thermodynamically stable. The stability order for the keto and enol isomers: Tce > Tte > Cte > E1 > E2 > E3, E4, E5 > E6 is the same at each level of computations. The keto Tce structure has the lowest Gibbs free energy (G). The G value of the most stable enol E1 structure is larger than those of the three keto structures by a few kcal mol-1.