How many postulates of quantum mechanics ?

There are four postulates of quantum mechanics:-

 POSTULATE I.

 For any possible state of a system, there is a function,

, of the coordinates of the parts of the system and time that completely describes the system.

For a single particle described by Cartesian coordinates, we can write

                                                              Psi = psi(x,y,z,t)

POSTULATE II.

 For every dynamical variable (classical observable) there is a corresponding operator.

POSTULATE III.

 The permissible values that a dynamical variable may have are those given by αφ = aφ, where φ is the eigenfunction of the operator α that corresponds to the observable whose permissible values are a.

This postulate can be stated in the form of an equation as

Α operator .φ wave function = a constant (eigenvalue). φ. wave function

POSTULATE IV.

The state function,

, is given as a solution of ˆ H

=E

,  where ˆ H is the operator for total energy, the Hamiltonian operator.