Lattice points at the corners of the parallelepiped and at the centre of each

# Lattice points at the corners of the parallelepiped

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Lattice points at the corners of the parallelepiped and at the centre of each face of the unit cell. I type F type Bodycentered Lattice Facecentered Lattice Bodycentred/Facecentred Effective number of Lattice points / cell= = [1 (for corners)] + [1 (BC)] = 2 Effective number of Lattice points / cell= = [1 (for corners)] + [6 (1/2)] = 4
06-02-2020 15 Seven systems lead to 28 crystal structures:14 Bravais lattices 1. Triclinic ( a ≠ b≠c and a b ≠ 90) P , C, I, F 2. Monoclinic ( a ≠ b≠c and a = =90 ≠ b ) P, C, I, F 3. Orthorhombic ( a ≠ b≠c and a = b = =90 ) P , C, I, F 4. Trigonal/Rhombohedral ( a=b=c & a = b = ≠ 90 ) P, C , I , F 5. Hexagonal ( a= b≠c and a = b = =90 ) P, C, I, F 6. Tetragonal( a= b≠c and a = b =90 =120 ) P , C , I, F 7. Cubic ( a=b=c and a = b = =90 ) P, C , I, F Seven Systems Triclinic Body Centered Cell 2 Triclinic Primitive Cell 1 Triclinic BC Triclinic Primitive Seven Systems: Triclinic body-center Triclinic ( a ≠ b≠c and a b ≠ 90) Bravais Lattices The unit cell which has the smaller number of lattice points is chosen for the Bravais list