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      • Gaussian
        • Gaussview
          • Draw/Edit Molecule
          • Submit Calculations
        • Single Point Energy
          • Prepare Input
          • Gaussian Input File
          • Gaussian Output File
          • How Single Point Energy Works
          • Mathematics for Nerds
            • Born–Oppenheimer Approximation
            • Electronic Schrödinger Equation
            • Molecular Hamiltonian
            • Hartree Product
            • Slater Determinants
            • Hartree–Fock Approximation
            • Basis Set Expansion (LCAO Approximation)
            • Roothaan–Hall Equations
            • SCF Algorithm
            • Density Functional Theory
            • Hohenberg-Kohn Theorems
            • Kohn-Sham Equations
            • Exchange-Correlation Functionals
            • B3LYP Functional
            • Complete Single Point Energy Algorithm
        • Geometry Optimization
          • Optimization Input File
          • Optimization Output File
          • How Optimization Works
          • Mathematics for Nerds
            • Potential Energy Surface (PES)
            • Energy Gradient
            • Hessian Matrix
            • Taylor Series Expansion
            • Optimization Algorithm
            • Berny Optimization
            • Convergence Criteria
            • Complete Geometry Optimization Algorithm
        • Frequency Calculation
          • Frequency Input File
          • Frequency Output File
          • How Optimization Works
          • Mathematics for Nerds
            • Potential Energy Surface (PES) Near Equilibrium
            • The Harmonic Approximation
            • Hessian Matrix
            • Mass Weighted Coordinates
            • Normal Modes of Vibration
            • The Eigenvalue Problem
            • Vibrational Frequencies
            • IR Intensities
            • Thermodynamic Properties
            • Complete Frequency Algorithm
        • Optimization+Frequency Calculation
          • Input File
          • Output File
          • How Optimization+Frequency Works
          • Mathematics for Nerds
        • Transition State Optimization
          • Input File
          • Output File
          • How Optimization+Frequency Works
          • Mathematics for Nerds
            • Potential Energy Surface (PES) and Stationary Points
            • First-Order Saddle Points
            • Reaction Coordinate
            • Hessian Matrix and Negative Curvature
            • Rational Function Optimization
            • Berny Transition State Optimization
            • Initial Hessian and CalcFC
            • Transition State Verification Using Frequency Analysis
            • Complete Transition State Search Algorithm
        • Intrinsic Reaction Coordinate (IRC)
          • Input File
          • Output File
          • How IRC Works
          • Mathematics for Nerds
            • Minimum Energy Path (MEP)
            • Reaction Path Following
            • Mass Weighted Coordinates
            • Predictor-Corrector Algorithm
            • Step Size and Hessian Updates.
            • Complete IRC Algorithm
      • GAMESS
        • RHF
          • Input
          • Output
          • How RHF Works
          • Mathematics for Nerds
            • Electronic Schrödinger Equation
            • Born–Oppenheimer Approximation
            • Slater Determinants
            • Hartree–Fock Approximation
            • Fock Operator
            • Roothaan–Hall Equations
            • SCF Algorithm
            • Water Molecule Example
        • CIS
          • Input
          • Output
          • How CIS Works
          • Mathematics for Nerds
            • From RHF to CIS
            • Singly Excited Slater Determinants
            • Configuration Interaction Wavefunction
            • The CIS Hamiltonian
            • The CIS Secular Equation
            • Diagonalization and Excited States
            • Limitations of CIS
        • CASSCF
          • Active Space??
          • Input
            • Set Up
            • MCSCF Iterations
            • Electronic States and Configuration State Functions
            • Optimized Orbitals and Natural Orbitals
          • How CASSCF Works
          • Mathematics for Nerds
            • Why Hartree–Fock Fails
            • The Active Space Concept
            • Configuration State Functions (CSFs)
            • The CASSCF Wavefunction
            • The CASSCF Hamiltonian
            • Solving the Configuration Interaction Problem
            • Orbital Optimization
            • State-Averaged CASSCF
            • Density Matrices
            • Natural Orbitals
            • The Complete CASSCF Algorithm
        • XMCQDPT
          • Input
          • Output
          • How XMCQDPT Works
          • Mathematics for Nerds
            • Zeroth-Order Hamiltonian
            • Perturbation Expansion
            • Effective Hamiltonian
            • Intermediate-State Formalism
            • Second-Order Energy Corrections
            • Final XMCQDPT Energies
            • The Complete XMCQDPT Algorithm
      • ORCA
        • RHF
          • Input
          • Output
          • How RHF Works
          • Mathematics for Nerds
            • Complete RHF Algorithm
      • MCTDH
        • Operator
          • Prerequisites
          • Operator-make.sh
          • Script Explained
          • Operator.f90
          • Generated Operator File
          • Mathematics for Nerds
            • Vibrational Hamiltonian
            • Electronic Hamiltonian
            • Linear Vibronic Coupling
            • Quadratic Vibronic Coupling
            • Complete Vibronic Hamiltonian
            • Operator File Interpretation
        • Wavepacket Propagation
          • Input
          • Output
          • Population Analysis
          • Absorption Spectrum
          • How Wave Packet Propagation Works
          • Mathematics for Nerds
            • Time-Dependent Schrödinger Equation
            • Molecular Hamiltonian
            • Vibronic Hamiltonian
            • Linear Vibronic Coupling
            • Quadratic Vibronic Coupling
            • MCTDH Wavefunction Expansion
            • Single Particle Functions
            • Multi-Layer MCTDH (ML-MCTDH)
            • Dirac–Frenkel Variational Principle
            • Equations of Motion
            • Numerical Propagation Algorithms
            • Population Analysis
            • Autocorrelation Function
            • Absorption Spectrum
            • Complete Ml-MCTDH Wavepacket Propagation Algorithm
      • Featured Tutorials
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      • Latest Publications from our group
      • Jitendra Singh

    Latest Publications from our group

    Electronic spectroscopy of carbon chains (C2n+1, n = 7–10) of astrophysical importance. I. Quantum chemistry

    Journal of Chemical Physics  ·  2019

    Intramolecular Singlet Fission: Quantum Dynamical Simulations Including the Effect of the Laser Field

    Journal of Chemical Physics  ·  2024

    Quantum Dynamical Simulation of Intramolecular Singlet Fission in Covalently Coupled Pentacene Dimers

    The Journal of Chemical Physics  ·  2019

    Intramolecular Singlet Fission: Insights from Quantum Dynamical Simulations

    The Journal of Physical Chemistry Letters  ·  2018

    Theoretical Study of Intramolecular Singlet Fission in Xanthene-Bonded Pentacene Dimers

    Chemical Physics  ·  2018

    Investigation of Excited States of BODIPY Derivatives and Non-Orthogonal Dimers from the Perspective of Singlet Fission

    Physical Chemistry Chemical Physics  ·  2024

    Exploring Multiexciton Generation in an Asymmetric Aza-BODIPY Dimer

    Journal of Physical Chemistry A  ·  2026

    Metal-Directed Stereochemical Switching in Carboxylic Acid Addition to gem-Difluoroallenes

    ACS Catalysis  ·  2026

    Pd-Catalyzed Enantioselective Reductive Heck Reaction of mono-Fluoro, gem-Difluoro, and Trifluoromethyl Tethered-Alkenes

    Chemical Communications  ·  2025

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    Jitendra Singh

    TheoChem

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    Last Updated

    July 2026

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