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National Bird Day is celebrated every year on 5 January . This day is observed to spread awareness about birds, their importance in nature, and the need to protect them. Birds are beautiful living beings and play a very important role in keeping our environment healthy. Origin of National Bird Day National Bird Day was first celebrated in the year 2002 . It was started by bird lovers and environmental groups to protect birds from dangers like deforestation, pollution, and illegal hunting. The main aim of this day is to teach people, especially students, why birds are important and how we can help save them. Why Is National Bird Day Celebrated Every Year? National Bird Day is celebrated every year because many bird species are disappearing due to human activities. Cutting trees, using plastic, pollution, and climate change are harming birds and their homes. This day reminds us that: Birds need protection Nature should be respected Everyone has a responsibil...

Grand canonical ensemble | Statistical mechanics | L-9

Grand canonical ensemble

Grand canonical ensemble

  • Microcanonical ensemble is a collection of independent assemblies in which energy (E), volume (V), and number of particles (N) remain constant.
  • Canonical ensemble is a collection of independent assemblies in which temperature (T), volume (V), and number of particles (N) remain constant.
  • It mean a microcanonical ensemble ⟶ Canonical ensemble, if we ignore the condition E = constant.
  • Therefore the energy exchange takes place in this ensemble.
  • Actually in chemical process, the number of particles N varies and it is very difficult to keep the number of particles constant in various phenomenon like radioactive decay process.
  • Thus grand canonical ensemble is an ensemble in which the exchange of energy as well as the number of particles takes place with the heat reservoir.
  • The grand canonical ensemble is a collection of essentially independent assemblies having the same temperature T, volume V, and a chemical potential µ.

  • Thus grand canonical ensemble is a situation in which we know both the average energy and the average number of particles in assembly, otherwise we don’t know the state of the system.
  • The density function in Гspace for grand canonical ensemble = ρ (p, q, N)
  • Here p is momenta, q is coordinate and N is number of particles.
  • To find ρ (p, q, N), we consider the canonical ensemble for a system with particles N, volume V and temperature T.
  • Here we can not take exactly V = constant, so our focus is on a small sub-volume V1 of the system.
  • Let N1 particles be in volume V1, and N2 particles be in volume V2
  • N1 + N2 = N   ⇒   N2 = N - N1    and    V1 + V2 = V   ⇒   V2 = V - V1
  • Also we assume that V2 >> V1 and N2 >> N1
  • If H1 and H2 be the Hamiltonian of the system then
  • The total Hamiltonian of the composite system
  • H (p, q, N) = H1 (p1, q1, N1) + H2 (p2, q2, N2)

Partition function of the system

  • The partition function of the total system
  • Here A (N, V, T) is the Helmholtz free energy.
  • In the last term we consider that the system under consideration to become infinite in size or 0 ≤ N < ∞.
  • For thermodynamic function, we define grand partition function

Average number of particle

  • By ensemble average, the average number of particles

Internal energy

To know more about this topic please click the link https://youtu.be/1dpbmImt8UE

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