program Tinh_E



 implicit none

 save

 integer, parameter:: estep = 10

 integer :: i

 real(8), dimension(estep) :: E

 real(8) :: Ec, Ex  , k

 real(8), parameter :: pi= 3.141593

 real(8), parameter :: hbar = 658.d-3

 real, parameter :: L = 100.0                                           ! don vi nm

 real, parameter :: c = 3.0 * (10.0**(5))                            ! don vi nm/ps

 real, parameter :: n_cav =3.43

 real, parameter :: E0 = 1.515 *(10.0**(-6))                                       ! don vi meV

 real, parameter :: hbar_omega = 6.0                                              ! don vi meV

 real(8), parameter :: m_e = 0.067* 5.7*(10.0**3) , m_h = 0.45 *5.7*(10.0**3)



do i=1, estep

   k = real(i)*pi/L                                                   ! tinh gia tri cua k, don vi (nm^-1)



   Ec = (hbar*c/n_cav)*sqrt(pi/L  + k**2)



   Ex = E0 + hbar*(k**2)/(2.0*(m_e + m_h))



   E(i) = (1.0/2.0) * (Ec+Ex - sqrt((Ec- Ex)**2 + (hbar_omega)**2))



End do



 open (unit=2, file="/home/nap/Desktop/list_E.txt")



 do i=1, estep

  write (2, *) E(i)

 end do



End program tinh_e