B. Manna et Kk. Das, Ab initio based configuration interaction calculations on the low-lying electronic states of GaAs, J PHYS CH A, 102(48), 1998, pp. 9876-9883
Multireference singles and doubles configuration interaction calculations w
hich include relativistic effective core potentials have been performed on
GaAs. Potential energy curves of 40 Lambda-S states are computed. Spectrosc
opic constants (T-e, r(e), and omega(e)) of 17 bound Lambda-S states have b
een estimated and compared with the available observed and other calculated
values. The lowest Lambda-S state is ...pi(2) X(3)Sigma(-). All 22 Lambda-
S states which dissociate into Ga(P-2(u)) + As(S-4(u)) and Ga(P-2(u)) + As(
D-2(u)) limits are taken into consideration for the spin-orbit CI calculati
ons. Potential energy curves of 51 Omega-states are computed. The X(3)Sigma
(0+)(-) component is found to be the ground state of GaAs in contrary to th
e experimental findings which suggest the other component X(3)Sigma(1)(-) a
s the ground state. The splitting between the two components of X(3)Sigma(-
) is calculated to be 76 cm(-1) as compared with the experimental value of
43 cm(-1). The excited A(3)Pi(0+) state, which does not predissociate has r
(e) = 2.757 Angstrom, T-e = 22 178 cm(-1), and omega(e) = 125 cm(-1). T-e a
nd omega(e) values are somewhat smaller, while r(e) is larger than the obse
rved data. Transition probabilities of several dipole allowed transitions a
re calculated. Three transitions such as 1(1)Sigma(+)-4(1)Sigma(+), 2(1)Sig
ma(+)-4(1)Sigma(+), and X(3)Sigma(-)-A(3)Pi are found to be very strong. Th
e radiative lifetimes of many excited states are also estimated. The A(3)Pi
(0+) state at the vibrational level upsilon' = 0 has the calculated radiati
ve lifetime of 1050 ns which is somewhat larger than the observed range.