The words you are searching are inside this book. To get more targeted content, please make full-text search by clicking here.

progress with AOP mechanisms by QM computational Chemistry

Discover the best professional documents and content resources in AnyFlip Document Base.
Published by aram1121944, 2019-12-03 09:08:32


progress with AOP mechanisms by QM computational Chemistry

Keywords: AOP,Photocatlysis,TiO2,nano mateials



This HOMEPAGE enlists links for events
from 1998 to 2009, on the left-green pane

Profile & ebook links

E-Booklet for the occasion of RANCSD2019 at Department
of Chemistry MCC Tambaram CHENNAI

hot link to::------> A REPOSITORY


Copy of final draft of manuscript of Paper and a pdf copy of the Paper
Published in Indian Journal of Physics,Vol.79(9), p 985-989 (2005)
CMDAYS 2011, Gauhati University, Aug 24-26,2011

WMBS-I at NEHU , Shillong, 2010
WMBS-II at MZU , Aizawl, 2012
events_2012.html events-2013.html Full Paper for the ICETCS2013 Proceedings

Volume:- icetcs2013-fp-sa.pdf
event-2014 Delegate at 101st ISCA session
events-2015.html events-2016.html events-2017.html

Scope of Teaching & Research
events-2018.html events-2019.html Events Notice for participation in IUPAC2019,



Results: preceding events

CONTENT OF THESE 10 pages are excerpts from the Full paper submitted
for the NCCT 2018, presented at Ajmer


enumerated by illustrating with isolated water molecule Calculations:
Neutral, Oxidized and Reduced water are considered.

The QM computations are, some of them, by ab initio methods, but
subsequently semi empirical methods are used for quicker optimizations of
larger systems with and without charges. “What can happen to a water
molecule if it is optimized after added electrons or after removal of electrons”
has been the main emphasis before launching into the water clusters with
different number of charges, positive and negative.

In the Contribution to RANCSD2019, Chemistry Department, MCC, Chennai
the 12 water cluster is subjected to optimization by semi empirical AM1
method at the ARGUSLAB computational Chemistry PORTAL : obtainable
as internet resource free of charges, quicker to download and simple to install.
NMR Chemical shifts can reflect the charge movements at various stages of
optimization and illustrations explain how these can be providing information
for the bulk medium reactions with the prevailing intermolecular interactions.
No diffusion is included in the present consideration; only at every stage the
static cluster with the obtained disposition of water molecules is considered.
Random fluctuations would require time averaged situation and diffusion
would require a consideration of displacements of water molecules. These can
indicate how the bulk medium conditions can be regulated for increased
efficiency of photo catalytic process.



Life Member – Indian Science Congress Association:
In the above list find on Page 42:
L13931: Aravamudhan Sankarampadi, Ph.D., Professor Emeritus, Dept. of Chemistry, N.E.H.U.,
Shillong, 793022, MEGHALAYA

Page 1 of 11

Highlighting Certain Mechanistic Considerations: on the Use of
Semiconductor Metal Oxide Nano materials as photo catalyst.


(Deptt. of Chemistry, North Eastern Hill University, Shillong)
Ashiana Shubham Senior Living, Govindapuram, Maraimalainagar municipal limits

Chengalpattu 603204 Kancheepuram Dist Tamil Nadu
Abstract text:

Typical characteristics of heterogeneous catalysis consist of 5 stages as described in text books: (a) diffusion of
reactants to the surface (b) adsorption of reactants on to the surface (c) reaction on the surface (d) Desorption of
products from the surface and (e) diffusion of products from the surface. After the products formed on the surface
diffuse, there could be further follow up reactions in the bulk medium [R1] and final product that is of interest
would be available in the medium. In photo catalytic processes, typically in Advanced Oxidation/Reduction
Processes (AOP & ARP) , nano material (surface area criteria) semiconductors (band gap considerations) are used
[R2]. The surface reactions consists of electron or hole (as available after absorption of optical photons ) transfers
from photo catalyst to adsorbed reactants (or vice versa). Photo catalytic processes with nano semiconductor
materials have been effective for water splitting (hydrogen fuel) and decomposing toxic organic pollutants for water
purification. Particularly for water purifications decontaminating plants are being envisaged for large scale
purification of contaminated water and the efficiencies of such plants depend on the mechanisms [R3] in the five
stages mentioned above with surface and convenient photon frequency ranges for absorption by nano material (like
TiO2). Till now the efforts towards improving the efficiency of such plants have been putting together the various
experimental findings at the five stages (all independent of one stage from other). The electrochemical aspects with
electrode potential criteria (in Voltage units) with HOMO-LUMO relative energy of molecules (in electron volt
units) and the values in absolute energy units are required to be considered [R2] at all stages to logically build a
scheme for efficiency of plants.


R1. S. Aravamudhan, article in “A Monograph of Contributions Dr. S. Aravamudhan to Scientific Events”, page
128 (this is a reference containing an embedded pdf document
(of 418 pages ) of the book . It may take a long time top load this embedded document depending on internet
connection speeds. If there is a error message at the embedded form and instruction to download the document, click
and download the pdf document with Adobe reader. This Article is available at https://www.ugc-inno- and as an e-book

R2. National Convention of Chemistry Teachers – 2018 ,
2018.html#ncct2018 Presentation by S.Aravamudhan on “Photocatalytic water splitting……….”

R3. National Convention of Chemistry Teachers -2017,
Paper presented by S.Aravamudhan on “Computational Chemistry: Studies for increasing Efficiency of

AOP, ARP, Photo-catalysis, Water-splitting, Computational Chemistry, Nano Materials, Metal Oxide Semi
conductor Material.

Page 2 of 11

Power Point Presentation File:

An additional one-page elaboration: for the Abstract material to indicate the
specific content the contribution & presentation at RANCSD2019 at
Department of Chemistry, MCC, Chennai..

Page 3 of 11

Page 4 of 11

Page 5 of 11

Page 6 of 11

Below is a optimization by semi empirical QM method after charging the cluster
with 4 electrons.

If, at the surface, one
electron each has been
transferred to 4 of the
12 water molecules

As mentioned in the earlier frame, H2O is oxidized for the water
splitting reaction. Is it possible to know by Computational QC, what
would happen if electron gets transferred to water molecule?

All the following products can be identified in the optimized output above:

H2O + e = OH- +H OH- H + H = H2 H2 + OH- = H3O-
H2O + e = OH- +H
OH- + OH- = [H-O-O-H]2-

Results of a similar calculation, with 4 positive (instead of negative) charges on the
cluster, including added Oxygen when organic dye molecule is presented in the
following page.. With reduced oxygen molecules in the medium, degradation of
organic dye becomes evident. And, similar optimization with dye but with positive
charges does not produce as much evidence of disintegration of organic dye.

Page 7 of 11

In the following pages/sheets these above iterative steps are paused after
convenient few steps, the xyz file for the same. This partially (incomplete)
optimized disposition of water molecules is submitted for Proton NMR Chemical
shift calculations by HF ab initio method. And the NMR spectrum is obtained.
Then the optimization is resumed for few more steps and the process repeated until
complete convergence. The results are presented. For these calculation of NMR
spectra is convenient with the online portal . The limited, only
one minute CPU time was good enough for most of the cases.
These two jobs, 577690 and 577726 are for 12 molecule water cluster, drawn
a priory on the structure editor as guessed starting input, and was subjected to
geometry optimization with the result in 577726. This G.O. could be possible with
ARGUSLAB portal, and the xyz file saved from ARGUSLAB could be imported

Page 8 of 11

to the structure editor at for calculating chemical shift and the
NMR spectrum.

The water cluster is displayed in the figure above with the Proton NMR spectrum drawn
with 0.03 as line width parameter. This same spectrum could be plotted with1.0 value for
the line width parameter. These NMR spectra can be integrated to check that the total
number of protons was 24 from the start of the GO till the end, even though several
molecular species may occur as a consequence of GO scheme. IN the case of the above
12 molecules, there were 12 identifiable water molecules from the beginning till the end
of G.O. The 1772 steps of optimization have caused the NMR spectrum to be shifted by
4ppm towards the more shielded direction. In the beginning and as well as the end the
cluster of water molecules has been neutral without any electron transfers to or from
the system.

Page 9 of 11

The red colored line is the integrated curve of the blue spectral line. And the green
line corresponding to the height is proportional to the integrated area under the
spectral curve.

Page 10 of 11

Page 11 of 11

4.5 ppm

8.2 ppm

The proton locations in the cluster have been marked (with distinct numbers) and
their corresponding NMR line position are also marked on the spectrum. For a 20
steps of iteration with 2 +ve charges, a remarkable shift of Proton 27 is noticeable
towards the deshielded direction. Thus during the total number of 854 steps (for
convergence) such details reveal what could be the driving forces for the changes
in molecular coordinates and hence clue to the mechanisms (by tracking charges
on protons that undergo drastic changes in chemical shift values). Mulliken
charges on atoms are also displayed in the QM calculation output which can
quantitatively account for the trends. The water molecules with O1 and O34 do not
significantly change on the monitor visuals during the optimization. Conspicuous
changes are at the nearby water molecules. Such kind of specific differences have
been included in the Power Point presentation slides for the case of 2 positive
charges on water cluster and subsequently two negative charges on the cluster.

Dr. S. Aravamudhan
Professor (retired after superannuation on 30th November 2006)
Adjunct Faculty (as N.E.H.U. Pensioner);
North Eastern Hill University

Specialization: Quantum Chemistry, Magnetic Resonance Spectroscopy
ESR, NMR, High Resolution NMR in Liquids, High Resolution PMR in Solids, Nuclear Quadrupole
Resonance (webpage cited #5 below)

Publications: Total of about 10 in International & Indian Journals
Participated in (nearly 80 in number) National (held in INDIA) and International Conferences (held
in INDIA and Other Countries) and has made significant contributions in the field of research
specialization. (webpage cited #2 below)

Educational: (webpage cited #1 below)
Higher Secondary School Leaving Certificate, Z.P.M.P.High School,Chittoor,Andhra Pradesh
(A.P.),India ,year 1962
B.Sc., Mathematics,Physics and Chemistry(general), Government Arts and Science College,
Chittoor, A.P.,India , 1962-1965 Grade Obtained: Distinction (marks >75%) with university second
rank of merit.
M.Sc., Physical Chemistry, Sri Venkateswara University, Tirupati,A.P.Grade Obtained: A+ (68%-
75%), year 1968
Ph.D., Department of Chemistry, Indian Institute of Technology,Kanpur,U.P., India Thesis on:
Experimental Studies in Overhauser Effect in Free Radical Solutions, year 1975 - for a glimpse
of the Synopsis of the Thesis

Professional Positions (with dates): (webpage cited #2 below)
Demonstrator in Physics, G.A & S College, chittoor, Andhra Pradesh,India, year 1965-66
Post Doctoral Fellow,Max planck Gesselschaft, at Max planck Institute fur Medizinische forschung,
Abteilung Molekulare Physik. Heidelberg, Germany , year 1975-77 in the research area of High
Resolution NMR in Solids: multiple pulse line-narrowing experiments for the determination of
Shielding Tensors of Proton in single crystals of organic molecules. Experimental design and
construction of rf Probes for the proton enhanced rare nuclei detection of N15 containing single-
crystal specimen.
An extendable-basis adhock appointment as wissenschaftliche mitarbeiter in the Fach Bereich Physik
at the Institut fur Atom und Fest Krper Physik, Free University of Berlin, Berlin Germany in the
Sonder Forschungs Bereich: Optical Nuclear (proton) Polarisation Enhanced detection of Rare
Nuclei by Hartmann-Hahn proton polarisation transfer technique followed by rare spin FID detection
for the determination of the Shielding Tensors of Rare Nulclei. Year 1977-78.
As Scientist at National Chemical Laboratory, Pune, India during 1979-80. at the FT NMR facility of
NCL. As Research Associate at the Department of Chemistry, Indian Institute of Technology,
Kanpur,U.P., India in the research project on Multiple Pulse Line Narrowing Technique for Nuclear
Quadrupole Resonance Studies, during 1982-83.
Since 1985, Dr.Aravamudhan had been Teaching Physical Chemistry with Research in Magnetic
Resonance & Quantum Chemistry at the Department of Chemistry, North Eastern Hill University,
Shillong, 793022.

Sankarampadi ARAVAMUDHAN
Date of Birth: 01-12-1944; Place of Birth: Madras, JNDIA
Date of Superannuation: 30th Nov. 2006
Web Pages cited below as references:


Click to View FlipBook Version