A large unit cell semiempirical molecular orbital approach to the properties of solids. II. Covalent materials: diamond and silicon

Harker, A. H.; Larkins, Frank P.

doi:10.1088/0022-3719/12/13/014

Cited by 56 publications

(35 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is a pure quantum-mechanical effect and is directly related to the uncertainty principle. The cohesive energy value of the present work has better agreement with the experimental value [25] than the Harker and Larkins [5] value. This is because of the inclusion of the exchange integrals, correlation correction, and zero-point energy in our analysis.…”

Section: Electronic and Structural Propertiessupporting

confidence: 69%

“…The optimum values of these empirical parameters used for diamond in the present work are listed in Table 1 in comparison with the corresponding values of Harker and Larkins [5].…”

Section: Optimum Parameter Setmentioning

confidence: 99%

“…The special symmetry points in the Brillouin zone, which are effectively taken into account in the band-structure calculations, are Γ 25 , Γ 1 , Γ 15 , and X 4C . It should be pointed out that the increase of the LUC size will result in an increase of the results accuracy [5], but this complicates the calculations and needs a very long time in comparison with the time needed for 8-atom LUC calculations.…”

Section: Original Papermentioning

confidence: 99%

See 2 more Smart Citations

Semiempirical LUC‐INDO calculations on the effect of pressure on the electronic structure of diamond

Radi

Abdulsattar

Abdul-Lettif³

2007

Physica Status Solidi (b)

View full text Add to dashboard Cite

A self-consistent LUC (large unit cell) formalism on the basis of semiempirical INDO (intermediate neglect of differential overlap) Hamiltonians has been used to study the electronic properties of diamond and to investigate the pressure dependence of these properties. The calculated properties are in good agreement with the experiments except the conduction-band width. The increase of pressure on diamond is predicted to cause the following effects; an increase of the valence and conduction-band widths with a decrease of the direct bandgap, an increase of the electronic occupation probability for the p-orbital with a decrease of this probability for the s-orbital, and a decrease of the X-ray scattering factor.

show abstract

Section: Electronic and Structural Propertiessupporting

confidence: 69%

“…The optimum values of these empirical parameters used for diamond in the present work are listed in Table 1 in comparison with the corresponding values of Harker and Larkins [5].…”

Section: Optimum Parameter Setmentioning

confidence: 99%

Section: Original Papermentioning

confidence: 99%

See 1 more Smart Citation

Semiempirical LUC‐INDO calculations on the effect of pressure on the electronic structure of diamond

Radi

Abdulsattar

Abdul-Lettif³

2007

Physica Status Solidi (b)

View full text Add to dashboard Cite

show abstract

“…So it has amazing aspects [10] of multiuse [11,12] such as in polishing, cutting [13] and protection [14], and it has been the core for many studies [15][16][17][18] since its discovery in 1957 [19]. Methods of semiempirical calculations give a privilege of reasonable computer execution time for getting the results due to the approximations which are involved [20,21], accordingly they are used in many studies [22][23][24][25]. In this paper we have used linear combination of atomic orbitals (LCAO) approach as a starting point [26] which includes both 1) the CNDO, as one of the primary semiempirical methods, that is presented by Popel et al [27] in which many electron-electron interactions had been neglected.…”

Section: Introductionmentioning

confidence: 99%

Thermal dependence of the properties of cubic boron nitride crystal

Mijbil¹,

Abdulsattar²,

Abdul-Lettif³

2011

View full text Add to dashboard Cite

Lattice constant, total energy, cohesive energy, bulk modulus, speed of sound (υ), plasmon energy (E pl ), valence charge distribution and energy bands of cubic boron nitride crystal have been calculated and studied as a function of temperature using self-consistent field tight binding method with complete neglect of differential overlap version 2 using 8-atom large unit cell approach. Our results illustrate that the increase of temperature leads to an increase of lattice constant, cohesive energy, and valence charge distribution at the atoms, whereas a decrease is obtained for bulk modulus, energy band widths, valence charge distribution in the intratomic distance, speed of sound, and the plasmon energy. The comparison with experimental and other theoretical results has showed an excellent agreement for the lattice constant, bulk modulus, cohesive energy, speed of sound, plasmon energy value and the valence band, whereas remarkable differences in charge distribution values, and the band gap are found. These differences are common in the results that depend on this type of calculation. Values for conduction band and speed of sound have not been found for comparison. Our relation for E pl -T fails but the υ-T relation is successful.

show abstract

“…These parameters were fixed previously by Harker and Larkins (1979) so as to fit the observed lattice parameter, cohesive energy and valence band width for the perfect crystal. We have used their values ( .…”

mentioning

confidence: 99%

Nature and diffusion of the self-interstitial in silicon

Masri

Harker

Stoneham

1983

J. Phys. C: Solid State Phys.

Self Cite

View full text Add to dashboard Cite

Abstract. We exploit self-consistent, semi-empirical molecular orbital calculations (CNDO) for large silicon clusters to characterise self-interstitials. Hexagonal (I+) and split (100) forms (I-and probably Io) are favoured among the several forms investigated. Possible extended high-temperature forms are not discussed. Our results imply Bourgoin-Corbett athermal diffusion in p-Si and low-activation energy classical motion in n-Si; local excitation enhanced motion is possible, though not verified, but local heating is unlikely. Results agree well with experiment, both for Si and in understanding the different behaviour of silicon and diamond.The energetic advantage of the split form predicted is also supported by the observed split impurity interstitials and unidentified defects, related to the self-interstitial, observed in structures similar to the split (100) form.The self-interstitial in silicon is a tantalising defect. It is one of the basic intrinsic defects, and one whose involvement is important in many solid-state processes from below 1 K to near the melting point of Si (for reviews see Watkins 1964Watkins ,1967Watkins ,1975 and Seeger et a1 1979). Yet there are no confirmed, direct observations of the self-interstitial. Several centres seen in spin resonance, internal friction or channelling might be isolated interstitials, but the consensus at present is that these are probably merely related centres. Evidence for the properties of this elusive defect relies on indirect, sometimes controversial, analyses and on the rates, natures and ranges of occurrence of solid state reactions. Our present calculations allow us to rationalise much of the lower-temperature data in a way which is consistent with corresponding but distinct results (both theoretical and experimental) for diamond.The experimental situation is one of considerable controversy. We may summarise the results concisely as follows. At the lowest temperatures (0.5-20 K), in p-Si only, replacement reactions occur which displace substitutional impurities X, into interstitial sites, the silicon interstitial moving to the vacated lattice site, i.e. Sii + X, + Xi. The long-range motion of the interstitial appears to be athermal, driven by the ionisation produced at the same time as the defect. Replacement processes are observed for X = B, Al; at higher temperatures, similar processes seem to occur for C and Ga. However, Ge is not displaced to an interstitial site. At intermediate temperatures (50-900 K) there are signs of interstitial motion in n-Si, though no evidence for athermal motion. Various studies give low motion energies in the range 0.4 eV (Watkins 1967) to 0.08 eV (Brown and Fathy 1981). At higher temperatures still (above 900K) evidence is from the

show abstract

A large unit cell semiempirical molecular orbital approach to the properties of solids. II. Covalent materials: diamond and silicon

Cited by 56 publications

References 16 publications

Semiempirical LUC‐INDO calculations on the effect of pressure on the electronic structure of diamond

Semiempirical LUC‐INDO calculations on the effect of pressure on the electronic structure of diamond

Thermal dependence of the properties of cubic boron nitride crystal

Nature and diffusion of the self-interstitial in silicon

Contact Info

Product

Resources

About