TABLE 3.
Calculated EHOMO, ELUMO, energy band gap (EL-EH), chemical potential (μ), electro-negativity (χ), global hardness (η), global softness (S), and global electrophilicity index (ω) at 298.15 K for nicotinamide (NIC), oxalic acid (OXA), and NIC-OXA (form I) salt using B3LYP/6-311++G (d, p).
| Molecule | EH (eV) | EL (eV) | EL-EH (eV) | χ (eV) | μ (eV) | η (eV) | S (eV) | ω (eV) | ΔNmax |
|---|---|---|---|---|---|---|---|---|---|
| NIC (API) | −7.3414 | −1.8058 | 5.5356 | 4.5736 | −4.5736 | 2.7678 | 0.1806 | 3.7788 | 1.6524 |
| OXA (coformer) | −8.1669 | −2.5002 | 5.6667 | 5.3335 | −5.3335 | 2.8333 | 0.1765 | 5.0200 | 1.8824 |
| NIC-OXA salt (monomer) | −6.0205 | −3.8161 | 2.2044 | 4.9183 | −4.9183 | 1.1022 | 0.4536 | 10.9734 | 4.4622 |
| NIC-OXA salt (dimer) | −5.4180 | −3.8284 | 1.5896 | 4.6232 | −4.6232 | 0.7948 | 0.6291 | 13.4461 | 5.8168 |