Dr. Ronald G. Selsby:



1955-1959   Brooklyn Technical High School

1959-1964   State University of New York at Binghamton (Harpur College)

                    BS in Chemistry and Physics

1965-1969  The Ohio State University

                    Ph.D. Physics



1968-1970   Radiation and Solid State Physics Laboratory

                    New York University

                    Research Scientist

1970- present University of Puerto Rico, Rio Piedras Department of Physics

1970-1973  Assistant Professor

1973-1977  Associate Professor

1977-          Professor



Research in Quantum Chemistry


(1968) R.G. Selsby and R.C. Nelson

The Measurement of the Ionization Potential of Homologous Series of Photo Conducting Organic Dyes.

Presented by R.G. Selsby at Symposium on Molecular Structure and Spectroscopy, Sept 3-6 at The Ohio State University.


(1969) R.G. Selsby and M. Sukigara

Self-Consistent Field Calculations of the Electronic States of Radicals.

J. Molecular Spectroscopy  29,  461-471


(1969) N. Petruzzella, Ronald G. Selsby, and R. C. Nelson

Regeneration of Sensitizing- Dye Molecules from a Substrate.

J. Optical Soc. Am. 59(1), 112-113


(1970) R.G. Selsby and R.C. Nelson

The Measurement and Calculation of Ionization Energy of Cationic Cyanine Dyes.

J. of Molecular  Spectroscopy 33, 1-18.


(1970) R.C. Nelson and R.G. Selsby

Ionization Energy of Dyes and the Mechanism of Spectral Sensitization.

Photographic Science and Eng.  14(5), 342-346.


(1974) G.M. Loubriel and R.G. Selsby

A Technique for Orbital Exponent Optimization in ab-initio HF-SCF-LCAO-MO Theory.

Int. J. Quantum Chem.  8, 547-557


(1975) R.G. Selsby   

Variable z Calculation for Self-Consistent Screening Parameters in ab initio HF Molecular Orbital Calculations.     

Int. J. Quantum Chem. 9(1),  83-102.  


A resolution of Roothaan's HF–SCF–LCAO–MO equations is proposed in which atomic
orbital exponents (ζ) are made dependent on the molecular charge distribution and included
in the self‐consistent scheme. Screening parameters so obtained are self‐consistent with
the molecular orbital coefficients and compare closely to optimum orbital exponents found
by other methods. The technique is applied to the ground, lowest positive, and lowest
negative ion states of the hydride series LiH, BH, and HF. Calculated potential curves are …

 (1977) R.G. Selsby, C. Machin and M.L. Hernandez 
A semi-empirical MO theory for Ionization Potentials and Electron
Affinities. I. Vertical values.      
Int. J. Quantum Chem. 11(1), 149-161.


(1977) R.G. Selsby and Alec Grimison 
A semi-empirical MO theory for ionization potentials and electron affinities.  II. Vertical and Adiabatic values, benzenoid and non-benzenoid aromatic hydrocarbons, and conjugated molecules with heteroatoms.    
Int. J. Quantum Chem. 11(4), 527-544.


(1990) R.G. Selsby, Philip Pennance and K.I. Barnhard

Application of the PPP Method to the Calculation of Ionization Potentials and Electron Affinities of Conjugated Organic Molecules.

Int. J. Quantum Chem. 37, 539-546


(2009) Juan C. Delgado, Yasuyuki Ishikawa and Ronald G. Selsby

The Calculated Ionization Potential and Electron Affinity of Cationic Cyanine Dyes.

Photochemistry and Photobiology 85(6), 1286-1298 doi: 10.1111/j.1751-1097.2009.00601.x.


The ionization potential (IP) and electron affinity (EA) of the isolated single dye molecule and a hypothetical isolated J-aggregated dimer are calculated as an energy difference between separately minimized ground and ionized states. Three quantum methods are employed: density functional theory (DFT) Gaussian03 B3LYP/6-311G** (++G**); DFT using Dmol(3); and a modification of CNDO/S, called CNDO/S-Dz, which is developed for rapid calculation of the IP and EA. Results indicate that for the monomer, 1,1'-dimethyl-2,2'carbocyanine chloride, the vertical IP and EA are 6.2 +/- 0.1 and 1.90 +/- 0.05 eV, respectively. This is consistent with the threshold IP and EA predicted by the Yianoulis and Nelson "Statistical Model" of spectral sensitization. For the isolated J-aggregated dimer, whose configuration is consistent with being adsorbed on a dielectric substrate, the calculations predict a value of 5.2 +/- 0.2 and 2.35 +/- 0.05 eV for the IP and EA, respectively. Significant charge density is removed from the halide anion in the ionization process. The HOMO of the dye molecule is an MO associated with the halide anion. Calculation of the isolated entities is a necessary preliminary step in the study of the IP and EA of the adsorbed dye monomer and aggregate.


(2013) Juan C. Delgado and R.G. Selsby

Density Functional Theory Calculations on Rhodamine B and Pinacyanol Chloride. Optimized Ground State; Dipole Moment, Vertical and Adiabatic Ionization Potentials and Electron Affinity; and Lowest Excited Triplet State

Photochemistry and Photobiology 89(1), 51-60



Research Organic Solid State Exciton Migration Theory


(1971) R.G. Selsby and C.E. Swenberg

Diffusion Theory of Luminescent Emission from a Doped Organic Solid.

Physica status solidi  50, 235-239


(1972) M. Pope and R.G. Selsby

Excitonic Sounding: A proposed Method for Measuring a Charge Density Gradient in Anthracene.

Chem. Phys. Letts. 14, 226-230


(1972) R.G. Selsby

The Applicability of Diffusion Theory to the Study of Luminescent Emission from a Doped Organic Crystal.

Physica status solidi  53(1); ibid. (b)55, K93-K96 (1973);  ibid. (b) 67, K69-K73 (1975);

 ibid. (b) 70, K96 (1975) 

The Frisch‐Collins diffusion theory, developed to handle the case of a plurality of competing traps in the diffusion field, is used to calculate the time dependence of the fluorescence both from host crystal and impurity trap in a doped organic solid. Satisfactory agreement is found between experiment and theory indicating that a theory of exciton diffusion can account for the excitation

(1976) S. Arnold, R.R. Alfano, M. Pope, W. Yu, P. Ho, R.G. Selsby, J. Tharrats and C.E. Swenberg  

Triplet Exciton Caging in Two Dimensions.

J. Chem. Phys. 64, 5104 - 5114      doi.org/10.1063/1.432184






GRANTS: (on which I was Co-Principal Investigator)


1976-1977  “Photo Induced electron Transfer States: A Possible source of Hydrogen”

                    ($40,000) from Center for Energy & Environmental Research, San Juan, PR

1976-1978   “Use of Computers in the Teaching of Physical Sciences & Mathematics”

                    ($307,600) NSF… In this project, I created the Natural Science Computer

                    center (installing the HP-2000), trained students to run the center and

                    eventually became the first Director of this entity.


                    Principal Investigator

1980-1982   CAUSE: Computer Assisted Instruction for Pre-Calculus

                    ($100,000) MISIP-NSF  






MASTERS DEGREE                                          Department

1971-1972   MS    Jose Marrero                            Physics

1972-1973   MS    Guillermo Loubriel                  Physics

1974-1975   MS    Magda Hernandez                    Physics

1977-1978   MS    Jose I. Rodriguez Rodriguez    Physics

1976-1977   MS    June Hime                                Biology

1983-1984   MS    Roberto Ribera Padilla             Physics

1988-1989   MS    Wilson Melendez                     Physics

1987-1989   MS    Katherine Barnhard                 Chemistry

2004-2005   MS    Rafael J. Rodriguez                 Physics



1986-1989   Ph.D.  Phillip Pennance                 (Chemical-Physics)

2001-2003   Ph.D.  Juan M. Gonzalez Juarbe   (Dept. of Education)

2006-2009   Ph.D.  Juan Carlos Delgado          (Chemical-Physics)








TEACHING  1970-present  (50 years at UPR-RP in June 2020)

University Physics General Course (3 credits)

University Physics (for Physics, Mathematics, and Science Majors) (4 credits)

Intermediate Mechanics  (3 credits)

Intermediate Electro-Magnetism  (3 credits)

Modern Physics  (3 credits)

Mathematical Physics (3 credits)