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Full-Text Articles in Chemistry

Developments Of Machine Learning Potentials For Atomistic Simulations, Howard Yanxon Dec 2020

Developments Of Machine Learning Potentials For Atomistic Simulations, Howard Yanxon

UNLV Theses, Dissertations, Professional Papers, and Capstones

Atomistic modeling methods such as molecular dynamics play important roles in investigating time-dependent physical and chemical processes at the microscopic level. In the simulations, energy and forces, sometimes including stress tensor, need to be recalculated iteratively as the atomic configuration evolves. Consequently, atomistic simulations crucially depend on the accuracy of the underlying potential energy surface. Modern quantum mechanical modeling based on density functional theory can consistently generate an accurate description of the potential energy surface. In most cases, molecular dynamics simulations based on density functional theory suffer from highly demanding computational costs. On the other hand, atomistic simulations based on …


Structures Of Disodium Hydrogen Citrate Monohydrate, Na2hc6h5o7(H2o), And Diammonium Sodium Citrate, (Nh4)2nac6h5o7, From Powder Diffraction Data, Jerry Hong '20, Shivang Bhaskar, Joseph T. Golab, James A. Kaduk Aug 2020

Structures Of Disodium Hydrogen Citrate Monohydrate, Na2hc6h5o7(H2o), And Diammonium Sodium Citrate, (Nh4)2nac6h5o7, From Powder Diffraction Data, Jerry Hong '20, Shivang Bhaskar, Joseph T. Golab, James A. Kaduk

Student Publications & Research

No abstract provided.


Analytic Gradients For State-Averaged Multiconfiguration Pair-Density Functional Theory, Thais R. Scott, Matthew R. Hermes, Andrew M. Sand, Meagan S. Oakley, Donald G. Truhlar, Laura Gagliardi Jul 2020

Analytic Gradients For State-Averaged Multiconfiguration Pair-Density Functional Theory, Thais R. Scott, Matthew R. Hermes, Andrew M. Sand, Meagan S. Oakley, Donald G. Truhlar, Laura Gagliardi

Scholarship and Professional Work - LAS

Analytic gradients are important for efficient calculations of stationary points on potential energy surfaces, for interpreting spectroscopic observations, and for efficient direct dynamics simulations. For excited electronic states, as are involved in UV–Vis spectroscopy and photochemistry, analytic gradients are readily available and often affordable for calculations using a state-averaged complete active space self-consistent-field (SA-CASSCF) wave function. However, in most cases, a post-SA-CASSCF step is necessary for quantitative accuracy, and such calculations are often too expensive if carried out by perturbation theory or configuration interaction. In this work, we present the analytic gradients for multiconfiguration pair-density functional theory based on SA-CASSCF …


Crystal Structures Of Two Isostructural Compounds: A Second Polymorph Of Dipotassium Hydrogen Citrate, K2hc6h5o7, And Potassium Rubidium Hydrogen Citrate, Krbhc6h5o7, Diana Gonzalez '20, Joseph T. Golab, Andrew J. Cigler, James A. Kaduk Jun 2020

Crystal Structures Of Two Isostructural Compounds: A Second Polymorph Of Dipotassium Hydrogen Citrate, K2hc6h5o7, And Potassium Rubidium Hydrogen Citrate, Krbhc6h5o7, Diana Gonzalez '20, Joseph T. Golab, Andrew J. Cigler, James A. Kaduk

Student Publications & Research

No abstract provided.


Diammonium Potassium Citrate, (Nh4)2kc6h5o7, Nilan V. Patel, Joseph T. Golab, James A. Kaduk May 2020

Diammonium Potassium Citrate, (Nh4)2kc6h5o7, Nilan V. Patel, Joseph T. Golab, James A. Kaduk

Student Publications & Research

No abstract provided.


Improving Biodiesel Through Pyrolysis: Direct Dynamics Investigations Into Thermal Decomposition Of Methyl Linoleate, Michael Bakker May 2020

Improving Biodiesel Through Pyrolysis: Direct Dynamics Investigations Into Thermal Decomposition Of Methyl Linoleate, Michael Bakker

MSU Graduate Theses

Dependence on petroleum and petrochemical products is unsustainable as it is both a finite resource and environmentally hazardous. Biodiesel is a proposed alternative, but has complications including possessing poor cold weather operability and lacking the ability to supplement other petrochemical products (e.g., ethylene, hexane, etc.) relied upon in society. Pyrolysis of biodiesel has demonstrated the formation of smaller hydrocarbons comprising many of these petrochemical products. Our aim is to computationally simulate the pyrolysis of methyl linoleate, the most prevalent component in biodiesel formed in the US (from soybean). We make use of unimolecular direct dynamics describing intramolecular processes, introducing Temperature …


Powder X-Ray Diffraction Of Flucytosine, C4h4fn3o, Nilan V. Patel, Joseph T. Golab, James A. Kaduk, Amy M. Gindhart, Thomas N. Blanton Mar 2020

Powder X-Ray Diffraction Of Flucytosine, C4h4fn3o, Nilan V. Patel, Joseph T. Golab, James A. Kaduk, Amy M. Gindhart, Thomas N. Blanton

Student Publications & Research

No abstract provided.


Crystal Structure Of Pantoprazole Sodium Sesquihydrate Form I, C16h14f2n3o4sna(H2o)1.5, Diana Gonzalez '20, Joseph T. Golab, James A. Kaduk, Amy M. Gindhart, Thomas N. Blanton Mar 2020

Crystal Structure Of Pantoprazole Sodium Sesquihydrate Form I, C16h14f2n3o4sna(H2o)1.5, Diana Gonzalez '20, Joseph T. Golab, James A. Kaduk, Amy M. Gindhart, Thomas N. Blanton

Student Publications & Research

No abstract provided.


Multiscale Modeling Of Structure-Function Relationships Of Organic Semiconductors, Shi Li Jan 2020

Multiscale Modeling Of Structure-Function Relationships Of Organic Semiconductors, Shi Li

Theses and Dissertations--Chemistry

While optoelectronic devices built from organic semiconductors (OSC) continue to find their way into the commercial landscape, there remain numerous challenges to overcome to supplant traditional semiconductors in many technologies. Chief among these are low performance metrics relative to devices with conventional semiconductors and device stability. In order to overcome these challenges, a wide range of new OSC and processing technologies have been developed. However, there remains limited fundamental understanding of the relationship between molecular structure, packing in the solid state, and the resulting materials properties. Here, we make use of multiscale molecular models and utilize classical all-atom molecular dynamic …


Combined Computational And Experimental Studies On Cysteine-Sulfadiazine Adduct Formation, Nursel Açar Selçuki̇, Emi̇ne Coşkun, Ender Bi̇çer Jan 2020

Combined Computational And Experimental Studies On Cysteine-Sulfadiazine Adduct Formation, Nursel Açar Selçuki̇, Emi̇ne Coşkun, Ender Bi̇çer

Turkish Journal of Chemistry

The electrochemical characterization of sulfadiazine-cysteine (SD-CYS) adduct formation was performed in phosphatebuffer(pH7)onthebasisofvoltammetriccurrentandpeakpotentialmeasurements. Duetotheassociationof cysteine with sulfadiazine, the reduction peak currents of mercuric and mercurous cysteine thiolates decreased and their peak potentials simultaneously shifted to less negative potentials. By using the current changes of mercurous cysteine thiolate, it was determined that cysteine and sulfadiazine are associated with a 1:1 stoichiometry with a conditional association constant of 1.99 ×10$^{4}$ M$^{-1}$. In addition to experimental studies, a computational approach was carried out to study the geometrical parameters, electron densities, and UV-Vis absorption spectra of sulfadiazine and SDCYS adduct in water. Calculated (B3LYP/6-311++G(d,p) level) …


Design, Synthesis, And Spasmolytic Activity Of Thiophene-Based Derivatives Via Suzukicross-Coupling Reaction Of 5-Bromothiophene-2-Carboxylic Acid: Their Structural Andcomputational Studies, Nasir Rasool, Hafiz Mansoor Ikram, Ammara Rashid, Nazia Afzal, Muhammad Ali Hashmi, Muhammad Naeem Khan, Ayesha Khan, Imran Imran, Hafiz Muhammad Abdur Rahman, Syed Adnan Ali Shah Jan 2020

Design, Synthesis, And Spasmolytic Activity Of Thiophene-Based Derivatives Via Suzukicross-Coupling Reaction Of 5-Bromothiophene-2-Carboxylic Acid: Their Structural Andcomputational Studies, Nasir Rasool, Hafiz Mansoor Ikram, Ammara Rashid, Nazia Afzal, Muhammad Ali Hashmi, Muhammad Naeem Khan, Ayesha Khan, Imran Imran, Hafiz Muhammad Abdur Rahman, Syed Adnan Ali Shah

Turkish Journal of Chemistry

In the current research work, a facile synthesis of a series of novel thiophene-based derivatives of 5-bromothiophene-2- carboxylic acid (1) have been synthesized. All analogs (5a-5e, 10a-10f) were obtained from the coupling reaction of 5-bromothiophene- 2-carboxylic acid (1) and different arylboronic acids with moderate-to-good yields under controlled and optimal conditions. The structures of the newly synthesized compounds were characterized through spectral analysis and their spasmolytic activity, and most of the compounds exhibited potentially good spasmolytic effect. Among the synthesized analogs, compound phenethyl 5-(3,4-dichlorophenyl)thiophene-2-carboxylate (10d) particular showed an excellent spasmolytic effect with an EC$_{50}$ value of 1.26. All of the compounds …


Quantum Chemical Pka Estimation Of Carbon Acids, Saturated Alcohols, And Ketones Via Quantitative Structure-Activity Relationships, Corey Adam Baldasare Jan 2020

Quantum Chemical Pka Estimation Of Carbon Acids, Saturated Alcohols, And Ketones Via Quantitative Structure-Activity Relationships, Corey Adam Baldasare

Browse all Theses and Dissertations

Acid dissociation constants, often expressed as pKa values, afford vital information with regards to molecular behavior in various environments and are of significance in fields of organic, inorganic, and medicinal chemistry. Several quantitative structure-activity relationships (QSARs) were developed that correlate experimental pKas for a given class of compounds with a descriptor(s) calculated using density functional theory at the B3LYP/6-31+G** level utilizing the CPCM solvent model. A set of carbon acids provided a good final QSAR model of experimental aqueous pKas versus ΔEH2O (R2 = 0.9647) upon removal of three aldehydes as outliers. A study of saturated alcohols offered a final …