The optimized geometry of HBr, based on the Double Zeta Valence (DZV) calculation. The bond length of Hbr, as determined by the DZV level of theory. The accepted bond length for HBr is 1.4144Å, so this is within the error of that value.¹

The electrostatic potential of HBr was mapped on the molecule. Red denotes high electron density, and blue denotes low electron density.

The Highest Occupied Molecular Orbital (HOMO) for HBr was calculated using DZV.
 
The Lowest Unoccupied Molecular Orbital (LUMO) for HBr was determined with the DZV level of theory.

The partial charges on hydrogen and bromine are depicted.


Table 1: HBr Molecular Orbitals and their corresponding energies and occupation numbers.

Occupation Number	Energy (Hartrees)	Bonding	Molecular Orbital
0	0.6641	nonbonding
0	0.1362	antibonding
2	-0.4349	nonbonding
2	-0.4349	nonbonding
2	-0.5758	nonbonding
2	-1.0317	bonding
2	-3.1933	nonbonding
2	-3.1933	nonbonding
2	-3.2094	nonbonding
2	-3.2094	nonbonding
2	-3.2094	nonbonding
2	-7.4577	nonbonding
2	-7.4577	nonbonding
2	-7.4684	nonbonding
2	-9.7026	nonbonding

Table 2: The dipole moments calculated at different levels of theory and diffuse functions.

(D,F,L)	3-21G Dipole Moment (D)	(D,F,L)	6-31G Dipole Moment (D)	(D,F,L)	DZV Dipole Moment (D)
(1,0,1)	1.050075	(1,0,1)	1.146264	(1,0,1)	1.097927
(2,0,2)	0.855275	(2,0,2)	0.978206	(2,0,2)	0.950998
(3,0,3)	0.893857	(3,0,3)	0.951680	(3,0,3)	0.961316

D=#D heavy atom polarization functions
F=#F heavy atom polarization funtions
L=# Light atom polarization functions

Table 3: The most accurate dipole moment value with the corresponding theoretical value.

Calculated	0.893857D
Theoretical	0.827D

The best dipole moment was determined to be the value calculated based on the 3-21G optimization.

Calculated Vibrational Frequency: 2635.8 1/cm


Figure 1: The potential energy of bond stretching for HBr. The three different levels of theory are all plotted on this graph.