BSc (First Class Honours) in Chemical Physics, University College London, 1990.
PhD in Chemistry, University College London, 1993.
Office: Salem 202
Phone: (336) 758-3713
Salam Group Members
|Grant Backerman||Hien Morris
Former Group Members
|Max Dosser||Yuguang Ma,
Currently at Texas A & M University
| Wes Farrell
|Asha Tipirneni||Yuhe Wang|
Theoretical Chemical Physics
A fundamental description is sought of the properties of molecules, their mutual interaction, and their interaction with electromagnetic fields. Current and future research areas of interest include long-range intermolecular forces, single- and multi-photon absorption and emission processes, and molecular chirality.
Specific Research Programs
1. Molecular Quantum Electrodynamics
Radiation-molecule and molecule-molecule interactions are described completely quantum mechanically using quantum electrodynamics. In this microscopic treatment of electron-photon interactions, the time evolution of the dynamically coupled radiation-matter system is followed and quantum mechanical probabilities are evaluated for a variety of chemical and physical processes. New approaches within this framework are presently being developed to enable the facile computation of the energy shift due to higher multipole moment contributions to the retarded van der Waals dispersion force. Other applications of the formalism involve calculation of transfer rates arising from the resonance exchange of energy, and transition rates for chiroptical and nonlinear optical spectroscopies such as induced circularly polarized luminescence and two-centre two-photon circular dichroism.
Molecular Quantum Electrodynamics: Long-Range Intermolecular Interactions
– Akbar Salam, John Wiley & Sons, Inc., NJ, 2010.
A. Salam, “Dispersion Potential Between Three-Bodies with Arbitrary Electric Multipole Polarizabilities: Molecular QED Theory, J. Chem. Phys. 140, 044111 1-12 (2014).
A. Salam, “Higher-Order Electric Multipole Contributions to Retarded Non-Additive Three-Body Dispersion Interaction Energies Between Atoms: Equilateral Triangle and Collinear Configurations”, J. Chem. Phys. 139, 244105 1-11 (2013) .
S. Y. Buhmann, H. Safari, S. Scheel and A. Salam, “Body-Assisted Dispersion Potentials of Diamagnetic Atoms”, Phys. Rev. A 87, 012507 1-10 (2013).
A. Salam, “Mediation of Resonance Energy Transfer by a Third Molecule”, J. Chem. Phys. 136, 014509 1-5 (2012).
A. Salam, “Molecular Quantum Electrodynamics of Radiation-Induced Intermolecular Forces”, Adv. Quant. Chem. 62, 1-34 (2011).
J. J. Rodriguez and A. Salam, “Effect of Medium Chirality on the Rate of Resonance Energy Transfer”, J. Phys. Chem. B115, 5183-5190 (2011).
J. J. Rodriguez and A. Salam, “On the Influence of Nonlocal Molecular Vibrations and Charge Transfer on the Spectra of Aggregated Push-Pull Chromophores”, J. Chem. Phys. 134, 154512 (2011).
J. J. Rodriguez and A. Salam, “Casimir-Polder Potential in a Dielectric Medium Out of Thermal Equilibrium”,Phys. Rev. A 82, 062522 1-6 (2010).
A. Salam and D. A. Micha, “Photoinduced Quantum Dynamics in Molecules and at Adsorbates”, Molec. Phys. 108, 3223-3234 (2010). Invited Article.
J. J. Rodriguez and A. Salam, “On the Role of Dissipation on the Casimir-Polder Potential Between Molecules in Dielectric Media”, J. Chem. Phys. 133, 164501 1-8 (2010).
J. J. Rodriguez and A. Salam, “Influence of Medium Chirality on Electric Dipole-Dipole Resonance Energy Transfer”, Chem. Phys. Lett. 498, 67-70 (2010).
P. Fischer and A.Salam, “Molecular QED of Coherent and Incoherent Sum-frequency and Second-harmonic Generation in Chiral Liquids in the Presence of a Static Electric Field”, Molec. Phys. 108, 1857-1868 (2010).
A. Salam, “On the Manifestation of Casimir Effects in Intermolecular Interactions via the Method of Induced Moments”, J. Phys. Conf. Ser. 161, 012040 1-14 (2009).
A. Salam, “Molecular Quantum Electrodynamics in the Heisenberg Picture: A Field Theoretic Viewpoint”, Int. Rev. Phys. Chem. 27, 405-448 (2008).
A. Salam, “Two Alternative Derivations of the Static Contribution to the Radiation-Induced Intermolecular Energy Shift”, Phys. Rev. A 76, 063402 1-5 (2007).
B. W. Alligood and A. Salam, “On the Application of State Sequence Diagrams to the Calculation of the Casimir-Polder Potential”, Molec. Phys. 105, 395-404 (2007).
A. Salam, “A General Formula Obtained From Induced Moments for the Retarded van der Waals Dispersion Energy Shift Between Two Molecules With Arbitrary Electric Multipole Polarizabilities: I. Ground State Interactions”, J. Phys. B: At. Mol. Opt. Phys. 39 , S651-S661 (2006).
A. Salam, “A General Formula Obtained From Induced Moments for the Retarded van der Waals Dispersion Energy Shift Between Two Molecules With Arbitrary Electric Multipole Polarizabilities: II. Excited State Interactions”, J. Phys. B: At. Mol. Opt. Phys. 39 , S663-S669 (2006).
A. Salam, “Intermolecular Interactions in a Radiation Field via the Method of Induced Moments”, Phys. Rev. A 73, 013406 1-8 (2006).
A. Salam, “On the Effect of a Radiation Field in Modifying the Intermolecular Interaction Between Two Chiral Molecules”, J. Chem. Phys. 124, 014302 1-6 (2006).
A. Salam, “Generalized Expressions for Resonant Excitation Transfer and Retarded Dispersion Energy Shifts Obtained Using Multipolar Quantum Electrodynamics”, Int. J. Quantum Chem. 105, 762-766 (2005).
A. Salam, “Resonant Transfer of Excitation Between Two Molecules Using Maxwell Fields”, J. Chem. Phys. 122, 044113 1-7 (2005).
A. Salam, “A General Formula for the Rate of Resonant Transfer of Energy Between Two Electric Multipole Moments of Arbitrary Order Using Molecular Quantum Electrodynamics”, J. Chem. Phys. 122, 044112 1-12 (2005).
A. Salam, “A Simple Route to the Energy Shift Between an Electrically Polarizable Molecule and a Magnetically Susceptible Molecule via the Electromagnetic Energy Density”, Molec. Phys. 102, 797-800 (2004).
2. Semi-Classical Radiation Theory
In this viewpoint, only matter is treated quantum mechanically, with the electromagnetic field considered as an external classical perturbation. Analytical rotating-wave approximation expressions in addition to “exact” numerical methods for the solution of the time dependent Schrödinger equation in the presence of a periodic potential, are used to compute state probabilities and absorption spectra. These and other techniques will be used to extend and apply a theory of the control of the relative populations of an enantiomeric pair undergoing excitation by a circularly polarized pulsed laser, as well as the calculation of single- and multi-photon circular dichroism rates.
Y. Ma and A. Salam, “Controlling State Populations of Enantiomers of Real Chiral Molecules by Using a Circularly Polarized Pulsed Laser”, Chem. Phys. Lett. 431, 247-252 (2006).
Y. Ma and A. Salam, “On Chiral Selectivity of Enantiomers Using a Circularly Polarized Pulsed Laser Under Resonant and Off-resonant Conditions”, Chem. Phys. 324, 367-375 (2006).
Y. Ma and A. Salam, “Calculation of Electronic Circular Dichroism Spectra by Rotating Wave Approximation”, Chem. Phys. 324, 622-630 (2006).
3. Applications of Electronic Structure Theory
High-level methods of electronic structure theory as implemented in various quantum chemical software packages are being used to investigate the conformational equilibria of n-alkanes and keto-enol tautomerism in cyclic conjugated ketones.
S. W. Paine and A. Salam, “Computational Study of Tautomerism and Aromaticity in Mono- and Dithio-Substituted Tropolone”, Int. J. Quant. Chem. 113, 1245-1252 (2013).
S. W. Paine and A. Salam, “A Computational Study of the Keto-Enol Equilibria of Sulphur Substituted Analogues of Hydroxycyclopropenone”, J. Mol. Struct. (THEOCHEM) 814, 105-112 (2007).
S. W. Paine and A. Salam, “Computational Study of Keto-Enol Equilibria of Tropolone in Gas and Aqueous Solution Phase”, Chem. Phys. 331, 61-66 (2006).
S. W Paine, A. J. Kresge, and A. Salam, “An Ab Initio and Density Functional Theory Study of Keto-Enol Equilibria of Hydroxycyclopropenone in Gas and Aqueous Solution Phase”, J. Phys. Chem. A 109, 4149-4153 (2005).