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Under standing atomic structure, combination of atoms

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When atoms combine, they gain or lose
(a) electrons
(b) neutrons
(c) protons
(d) nuclei
(e) all of the above
(f) none of the above

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Solution Summary

The standard atomic structures and combination of atoms are examined.

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Band structure and a weak periodic potential

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A weak periodic potential

W(z) = W_0 cos (2*pi*z)/a

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A simple model of a two-dimensional band structure can be obtained by summing together two one-dimentional band structures. Consider the energy band

E(k_x, k_y) = U cos (k_x * a) - U cos (k_y * a)

with U > 0, corresponding to a particular two-dimensional crystal with square lattice and period a. Give the wavevectors and energies of the highest and lowest energy states in teh band. Draw labelled constant energy contours in the first Brillouin zone near these particular states. Comment on the form of the constant-energy contours near the centre fo teh first Brillouin zone.

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