Q-Chem 5.2 User’s Manual

Contents

• 1 Introduction
  • 1.1 About This Manual
  • 1.2 Q-Chem, Inc.
    • 1.2.1 Contact Information and Customer Support
    • 1.2.2 About the Company
    • 1.2.3 Company Mission
  • 1.3 Q-Chem Features
    • 1.3.1 New Features in Q-Chem 5.2
    • 1.3.2 New Features in Q-Chem 5.1
    • 1.3.3 New Features in Q-Chem 5.0
    • 1.3.4 New Features in Q-Chem 4.4
    • 1.3.5 New Features in Q-Chem 4.3
    • 1.3.6 New Features in Q-Chem 4.2
    • 1.3.7 New Features in Q-Chem 4.1
    • 1.3.8 New Features in Q-Chem 4.0.1
    • 1.3.9 New Features in Q-Chem 4.0
    • 1.3.10 Summary of Features in Q-Chem versions 3.$$x
    • 1.3.11 Summary of Features Prior to Q-Chem 3.0
  • 1.4 Citing Q-Chem
• 2 Installation, Customization, and Execution
  • 2.1 Installation Requirements
    • 2.1.1 Execution Environment
    • 2.1.2 Hardware Platforms and Operating Systems
    • 2.1.3 Memory and Disk Requirements
  • 2.2 Installing Q-Chem
  • 2.3 Q-Chem Auxiliary files ($QCAUX)
  • 2.4 Q-Chem Run-time Environment Variables
  • 2.5 User Account Adjustments
  • 2.6 Further Customization: .qchemrc and preferences Files
  • 2.7 Running Q-Chem
  • 2.8 Parallel Q-Chem Jobs
  • 2.9 IQmol Installation Requirements
  • 2.10 Testing and Exploring Q-Chem
• 3 Q-Chem Inputs
  • 3.1 IQmol
  • 3.2 General Form
  • 3.3 Molecular Coordinate Input ($molecule)
    • 3.3.1 Specifying the Molecular Coordinates Manually
    • 3.3.2 Reading Molecular Coordinates from a Previous Job or File
  • 3.4 Job Specification: The $rem Input Section
  • 3.5 Additional Input Sections
  • 3.6 Multiple Jobs in a Single File: Q-Chem Batch Jobs
  • 3.7 Q-Chem Output File
• 4 Self-Consistent Field Ground-State Methods
  • 4.1 Overview
  • 4.2 Theoretical Background
    • 4.2.1 SCF and LCAO Approximations
    • 4.2.2 Hartree-Fock Theory
  • 4.3 Basic SCF Job Control
    • 4.3.1 Overview
    • 4.3.2 Additional Options
    • 4.3.3 Examples
    • 4.3.4 Symmetry
  • 4.4 SCF Initial Guess
    • 4.4.1 Introduction
    • 4.4.2 Simple Initial Guesses
    • 4.4.3 Reading MOs from Disk
    • 4.4.4 Modifying the Occupied Molecular Orbitals
    • 4.4.5 Basis Set Projection
  • 4.5 Converging SCF Calculations
    • 4.5.1 Introduction
    • 4.5.2 Basic Convergence Control Options
    • 4.5.3 Direct Inversion in the Iterative Subspace (DIIS)
    • 4.5.4 Geometric Direct Minimization (GDM)
    • 4.5.5 Direct Minimization (DM)
    • 4.5.6 Maximum Overlap Method (MOM)
    • 4.5.7 Relaxed Constraint Algorithm (RCA)
    • 4.5.8 User-Customized Hybrid SCF Algorithm
    • 4.5.9 Internal Stability Analysis and Automated Correction for Energy Minima
    • 4.5.10 Small-Gap Systems
  • 4.6 Large Molecules and Linear Scaling Methods
    • 4.6.1 Introduction
    • 4.6.2 Continuous Fast Multipole Method (CFMM)
    • 4.6.3 Linear Scaling Exchange (LinK) Matrix Evaluation
    • 4.6.4 Incremental and Variable Thresh Fock Matrix Building
    • 4.6.5 Fourier Transform Coulomb Method
    • 4.6.6 Resolution of the Identity Fock Matrix Methods
    • 4.6.7 PARI-K Fast Exchange Algorithm
    • 4.6.8 CASE Approximation
    • 4.6.9 occ-RI-K Exchange Algorithm
  • 4.7 Dual-Basis Self-Consistent Field Calculations
    • 4.7.1 Dual-Basis MP2
    • 4.7.2 Dual-Basis Dynamics
    • 4.7.3 Basis-Set Pairings
    • 4.7.4 Job Control and Example
  • 4.8 Hartree-Fock and Density-Functional Perturbative Corrections
  • 4.9 Unconventional SCF Calculations
    • 4.9.1 Polarized Atomic Orbital (PAO) Calculations
    • 4.9.2 SCF Metadynamics
    • 4.9.3 Multiple SCF Solutions for Non-Orthogonal CI
    • 4.9.4 Holomorphic Hartree–Fock Theory
  • 4.10 Ground State Method Summary
• 5 Density Functional Theory
  • 5.1 Introduction
  • 5.2 Kohn-Sham Density Functional Theory
  • 5.3 Overview of Available Functionals
    • 5.3.1 Suggested Density Functionals
    • 5.3.2 Exchange Functionals
    • 5.3.3 Correlation Functionals
    • 5.3.4 Exchange-Correlation Functionals
    • 5.3.5 Specialized Functionals
    • 5.3.6 User-Defined Density Functionals
  • 5.4 Basic DFT Job Control
  • 5.5 DFT Numerical Quadrature
    • 5.5.1 Angular Grids
    • 5.5.2 Standard Quadrature Grids
    • 5.5.3 Consistency Check and Cutoffs
    • 5.5.4 Multi-resolution Exchange-Correlation (MRXC) Method
    • 5.5.5 Incremental DFT
  • 5.6 Range-Separated Hybrid Density Functionals
    • 5.6.1 Semi-Empirical RSH Functionals
    • 5.6.2 User-Defined RSH Functionals
    • 5.6.3 Tuned RSH Functionals
    • 5.6.4 Tuned RSH Functionals Based on the Global Density-Dependent Condition
  • 5.7 DFT Methods for van der Waals Interactions
    • 5.7.1 Non-Local Correlation (NLC) Functionals
    • 5.7.2 Empirical Dispersion Corrections: DFT-D
    • 5.7.3 Exchange-Dipole Model (XDM)
    • 5.7.4 Tkatchenko-Scheffler van der Waals Model (TS-vdW)
    • 5.7.5 Many-Body Dispersion (MBD) Method
  • 5.8 Empirical Corrections for Basis Set Superposition Error
  • 5.9 Double-Hybrid Density Functional Theory
  • 5.10 Asymptotically Corrected Exchange-Correlation Potentials
    • 5.10.1 LB94 Scheme
    • 5.10.2 Localized Fermi-Amaldi (LFA) Schemes
  • 5.11 Derivative Discontinuity Restoration
  • 5.12 Thermally-Assisted-Occupation Density Functional Theory (TAO-DFT)
  • 5.13 Methods Based on “Constrained” DFT
    • 5.13.1 Theory
    • 5.13.2 CDFT Job Control and Examples
    • 5.13.3 Configuration Interaction with Constrained DFT (CDFT-CI)
    • 5.13.4 CDFT-CI Job Control and Examples
• 6 Wave Function-Based Correlation Methods
  • 6.1 Introduction
  • 6.2 Treatment and the Definition of Core Electrons
  • 6.3 Møller-Plesset Perturbation Theory
  • 6.4 Exact MP2 Methods
    • 6.4.1 Algorithm
    • 6.4.2 Algorithm Control and Customization
  • 6.5 Local MP2 Methods
    • 6.5.1 Local Triatomics in Molecules (TRIM) Model
    • 6.5.2 EPAO Evaluation Options
  • 6.6 Auxiliary Basis (Resolution of the Identity) MP2 Methods
    • 6.6.1 RI-MP2 Energies and Gradients.
    • 6.6.2 OpenMP Implementation of RI-MP2
    • 6.6.3 GPU Implementation of RI-MP2
    • 6.6.4 Spin-Biased MP2 Methods (SCS-MP2, SOS-MP2, and MOS-MP2)
    • 6.6.5 Orbital-Optimized MP2
    • 6.6.6 RI-TRIM MP2 Energies
    • 6.6.7 Dual-Basis MP2
  • 6.7 Attenuated MP2
  • 6.8 Coupled-Cluster Methods
    • 6.8.1 Coupled Cluster Singles and Doubles (CCSD)
    • 6.8.2 Quadratic Configuration Interaction (QCISD)
    • 6.8.3 Optimized Orbital Coupled Cluster Doubles (OD)
    • 6.8.4 Quadratic Coupled Cluster Doubles (QCCD)
    • 6.8.5 Resolution of the Identity with CC (RI-CC)
    • 6.8.6 Cholesky decomposition with CC (CD-CC)
    • 6.8.7 Job Control Options
    • 6.8.8 Examples
  • 6.9 Non-Iterative Corrections to Coupled Cluster Energies
    • 6.9.1 (T) Triples Corrections
    • 6.9.2 (2) Triples and Quadruples Corrections
    • 6.9.3 (dT) and (fT) corrections
    • 6.9.4 Job Control Options
    • 6.9.5 Examples
  • 6.10 Coupled Cluster Active Space Methods
    • 6.10.1 Introduction
    • 6.10.2 VOD and VOD(2) Methods
    • 6.10.3 VQCCD
    • 6.10.4 CCVB-SD
    • 6.10.5 Local Pair Models for Valence Correlations Beyond Doubles
    • 6.10.6 Convergence Strategies and More Advanced Options
  • 6.11 Frozen Natural Orbitals in CCD, CCSD, OD, QCCD, and QCISD Calculations
  • 6.12 Non-Hartree-Fock Orbitals in Correlated Calculations
  • 6.13 Analytic Gradients and Properties for Coupled-Cluster Methods
  • 6.14 Memory Options and Parallelization of Coupled-Cluster Calculations
  • 6.15 Using single-precision arithmetics in coupled-cluster calculations
  • 6.16 Simplified Coupled-Cluster Methods Based on a Perfect-Pairing Active Space
    • 6.16.1 Perfect pairing (PP)
    • 6.16.2 Coupled Cluster Valence Bond (CCVB)
    • 6.16.3 Second-order Correction to Perfect Pairing: PP(2)
    • 6.16.4 Other GVBMAN Methods and Options
  • 6.17 Geminal Models
  • 6.18 Variational Two-Electron Reduced-Density-Matrix Methods
    • 6.18.1 Introduction
    • 6.18.2 Theory
    • 6.18.3 v2RDM Job Control
    • 6.18.4 Examples
• 7 Open-Shell and Excited-State Methods
  • 7.1 General Excited-State Features
  • 7.2 Uncorrelated Wave Function Methods
    • 7.2.1 Single Excitation Configuration Interaction (CIS)
    • 7.2.2 Random Phase Approximation (RPA)
    • 7.2.3 Extended CIS (XCIS)
    • 7.2.4 Spin-Flip Extended CIS (SF-XCIS)
    • 7.2.5 Spin-Adapted Spin-Flip CIS
    • 7.2.6 CIS Analytical Derivatives
    • 7.2.7 Basic CIS Job Control Options
    • 7.2.8 CIS Job Customization
  • 7.3 Time-Dependent Density Functional Theory (TDDFT)
    • 7.3.1 Brief Introduction to TDDFT
    • 7.3.2 TDDFT within a Reduced Single-Excitation Space
    • 7.3.3 Job Control for TDDFT
    • 7.3.4 TDDFT Coupled with C-PCM for Excitation Energies and Properties Calculations
    • 7.3.5 Analytical Excited-State Hessian in TDDFT
    • 7.3.6 Calculations of Spin-Orbit Couplings Between TDDFT States
    • 7.3.7 Various TDDFT-Based Examples
  • 7.4 Non-Orthogonal Configuration Interaction (NOCI)
  • 7.5 Maximum Overlap Method (MOM) for SCF Excited States
  • 7.6 Restricted Open-Shell Kohn-Sham Method for $\mathrm{\Delta }$-SCF Calculations of Excited States
  • 7.7 Correlated Excited State Methods: The CIS(D) Family
    • 7.7.1 CIS(D) Theory
    • 7.7.2 Resolution of the Identity CIS(D) Methods
    • 7.7.3 SOS-CIS(D) Model
    • 7.7.4 SOS-CIS(D${}_0$) Model
    • 7.7.5 CIS(D) Job Control and Examples
    • 7.7.6 RI-CIS(D), SOS-CIS(D), and SOS-CIS(D${}_0$): Job Control
    • 7.7.7 Examples
  • 7.8 Coupled-Cluster Excited-State and Open-Shell Methods
    • 7.8.1 Excited States via EOM-EE-CCSD
    • 7.8.2 EOM-XX-CCSD and CI Suite of Methods
    • 7.8.3 Spin-Flip Methods for Di- and Triradicals
    • 7.8.4 EOM-DIP-CCSD
    • 7.8.5 EOM-DEA-CCSD
    • 7.8.6 EOM-CC Calculations of Core-Level States: Core-Valence Separation within EOM-CCSD
    • 7.8.7 EOM-CC Calculations of Metastable States: Super-Excited Electronic States, Temporary Anions, and More
    • 7.8.8 Charge Stabilization for EOM-DIP and Other Methods
    • 7.8.9 Frozen Natural Orbitals in CC and IP-CC Calculations
    • 7.8.10 Single-precision arithmetics in EOM-CC calculations
    • 7.8.11 Approximate EOM-CC Methods: EOM-MP2 and EOM-MP2T
    • 7.8.12 Approximate EOM-CC Methods: EOM-CCSD-S(D) and EOM-MP2-S(D)
    • 7.8.13 Implicit solvent models in EOM-CC/MP2 calculations.
    • 7.8.14 EOM-CC Jobs: Controlling Guess Formation and Iterative Diagonalizers
    • 7.8.15 Equation-of-Motion Coupled-Cluster Job Control
    • 7.8.16 Examples
    • 7.8.17 Non-Hartree-Fock Orbitals in EOM Calculations
    • 7.8.18 Analytic Gradients and Properties for the CCSD and EOM-XX-CCSD Methods
    • 7.8.19 EOM-CC Optimization and Properties Job Control
    • 7.8.20 EOM(2,3) Methods for Higher-Accuracy and Problematic Situations (CCMAN only)
    • 7.8.21 Active-Space EOM-CC(2,3): Tricks of the Trade (CCMAN only)
    • 7.8.22 Job Control for EOM-CC(2,3)
    • 7.8.23 Non-Iterative Triples Corrections to EOM-CCSD and CCSD
    • 7.8.24 Potential Energy Surface Crossing Minimization
    • 7.8.25 Dyson Orbitals for Ionized or Attached States within the EOM-CCSD Formalism
    • 7.8.26 Interpretation of EOM/CI Wave Functions and Orbital Numbering
  • 7.9 Correlated Excited State Methods: The ADC($n$) Family
    • 7.9.1 The Algebraic Diagrammatic Construction (ADC) Scheme
    • 7.9.2 Resolution of the Identity ADC Methods
    • 7.9.3 Spin Opposite Scaling ADC(2) Models
    • 7.9.4 Core-Excitation ADC Methods
    • 7.9.5 Spin-Flip ADC Methods
    • 7.9.6 Properties and Visualization
    • 7.9.7 Excited States in Solution with ADC/SS-PCM
    • 7.9.8 Frozen-Density Embedding: FDE-ADC methods
    • 7.9.9 ADC Job Control
    • 7.9.10 Examples
  • 7.10 Restricted Active Space Spin-Flip (RAS-SF) and Configuration Interaction (RAS-CI)
    • 7.10.1 The Restricted Active Space (RAS) Scheme
    • 7.10.2 Second-Order Perturbative Corrections to RAS-CI
    • 7.10.3 Short-Range Density Functional Correlation within RAS-CI
    • 7.10.4 Excitonic Analysis of the RAS-CI Wave Function
    • 7.10.5 Job Control for the RASCI1 Implementation
    • 7.10.6 Job Control Options for RASCI2
    • 7.10.7 Examples
  • 7.11 Core Ionization Energies and Core-Excited States
    • 7.11.1 Calculations of Core-Level States with (TD)DFT
    • 7.11.2 Examples
  • 7.12 Real-Time SCF Methods (RT-TDDFT, RT-HF, OSCF2)
  • 7.13 Visualization of Excited States
    • 7.13.1 Attachment/Detachment Density Analysis
    • 7.13.2 Natural Transition Orbitals
• 8 Basis Sets
  • 8.1 Introduction
  • 8.2 Built-In Basis Sets
  • 8.3 Basis Set Symbolic Representation
    • 8.3.1 Customization
  • 8.4 User-Defined Basis Sets ($basis)
    • 8.4.1 Introduction
    • 8.4.2 Job Control
    • 8.4.3 Format for User-Defined Basis Sets
  • 8.5 Mixed Basis Sets
  • 8.6 Dual Basis Sets
  • 8.7 Auxiliary Basis Sets for RI (Density Fitting)
  • 8.8 Ghost Atoms and Basis Set Superposition Error
• 9 Effective Core Potentials
  • 9.1 Introduction
  • 9.2 ECP Fitting
  • 9.3 Built-In ECPs
  • 9.4 User-Defined ECPs
  • 9.5 ECPs and Electron Correlation
  • 9.6 Forces and Vibrational Frequencies with ECPs
  • 9.7 A Brief Guide to Q-Chem’s Built-In ECPs
    • 9.7.1 The fit-HWMB ECP at a Glance
    • 9.7.2 The fit-LANL2DZ ECP at a Glance
    • 9.7.3 The fit-SBKJC ECP at a Glance
    • 9.7.4 The fit-CRENBS ECP at a Glance
    • 9.7.5 The fit-CRENBL ECP at a Glance
    • 9.7.6 The SRLC ECP at a Glance
    • 9.7.7 The SRSC ECP at a Glance
    • 9.7.8 The Karlsruhe “def2” ECP at a Glance
• 10 Exploring Potential Energy Surfaces: Critical Points and Molecular Dynamics
  • 10.1 Equilibrium Geometries and Transition-State Structures
    • 10.1.1 Overview
    • 10.1.2 Job Control
    • 10.1.3 Hessian-Free Characterization of Stationary Points
  • 10.2 Improved Algorithms for Transition-Structure Optimization
    • 10.2.1 Freezing String Method
    • 10.2.2 Hessian-Free Transition-State Search
    • 10.2.3 Improved Dimer Method
  • 10.3 Constrained Optimization
    • 10.3.1 Geometry Optimization with General Constraints
    • 10.3.2 Frozen Atoms
    • 10.3.3 Dummy Atoms
    • 10.3.4 Dummy Atom Placement in Dihedral Constraints
    • 10.3.5 Additional Atom Connectivity
    • 10.3.6 Application of External Forces
  • 10.4 Potential Energy Scans
  • 10.5 Intrinsic Reaction Coordinate
  • 10.6 Nonadiabatic Couplings and Optimization of Minimum-Energy Crossing Points
    • 10.6.1 Nonadiabatic Couplings
    • 10.6.2 Job Control and Examples
    • 10.6.3 Minimum-Energy Crossing Points
    • 10.6.4 Job Control and Examples
    • 10.6.5 State-Tracking Algorithm
  • 10.7 Ab Initio Molecular Dynamics
    • 10.7.1 Overview and Basic Job Control
    • 10.7.2 Additional Job Control and Examples
    • 10.7.3 Thermostats: Sampling the NVT Ensemble
    • 10.7.4 Vibrational Spectra
    • 10.7.5 Quasi-Classical Molecular Dynamics
    • 10.7.6 Fewest-Switches Surface Hopping
  • 10.8 Ab Initio Path Integrals
    • 10.8.1 Theory
    • 10.8.2 Job Control and Examples
• 11 Molecular Properties and Analysis
  • 11.1 Introduction
  • 11.2 Wave Function Analysis
    • 11.2.1 Population Analysis
    • 11.2.2 Multipole Moments
    • 11.2.3 Symmetry Decomposition
    • 11.2.4 Localized Orbital Bonding Analysis
    • 11.2.5 Basic Excited-State Analysis of CIS and TDDFT Wave Functions
    • 11.2.6 General Excited-State Analysis
  • 11.3 Interface to the NBO Package
  • 11.4 Orbital Localization
  • 11.5 Visualizing and Plotting Orbitals, Densities, and Other Volumetric Data
    • 11.5.1 Visualizing Orbitals Using MolDen and MacMolPlt
    • 11.5.2 Visualization of Natural Transition Orbitals
    • 11.5.3 Generation of Volumetric Data Using $plots
    • 11.5.4 Direct Generation of “Cube” Files
    • 11.5.5 NCI Plots
    • 11.5.6 Electrostatic Potentials
    • 11.5.7 ELF Plots
  • 11.6 Spin and Charge Densities at the Nuclei
  • 11.7 Atoms in Molecules
  • 11.8 Distributed Multipole Analysis
  • 11.9 Intracules
    • 11.9.1 Position Intracules
    • 11.9.2 Momentum Intracules
    • 11.9.3 Wigner Intracules
    • 11.9.4 Intracule Job Control
    • 11.9.5 Format for the $intracule Section
  • 11.10 Harmonic Vibrational Analysis
    • 11.10.1 Job Control
    • 11.10.2 Isotopic Substitutions
    • 11.10.3 Partial Hessian Vibrational Analysis
    • 11.10.4 Localized Mode Vibrational Analysis
  • 11.11 Anharmonic Vibrational Frequencies
    • 11.11.1 Vibration Configuration Interaction Theory
    • 11.11.2 Vibrational Perturbation Theory
    • 11.11.3 Transition-Optimized Shifted Hermite Theory
    • 11.11.4 Job Control
  • 11.12 Linear-Scaling Computation of Electric Properties
    • 11.12.1 $fdpfreq Input Section
    • 11.12.2 Job Control for the MOProp Module
    • 11.12.3 Examples
  • 11.13 NMR and Other Magnetic Properties
    • 11.13.1 NMR Chemical Shifts and J-Couplings
    • 11.13.2 Linear-Scaling NMR Chemical Shift Calculations
    • 11.13.3 Additional Magnetic Field-Related Properties
  • 11.14 Finite-Field Calculation of (Hyper)Polarizabilities
    • 11.14.1 Numerical Calculation of Static Polarizabilities
    • 11.14.2 Romberg Finite-Field Procedure
  • 11.15 General Response Theory
    • 11.15.1 Job Control
    • 11.15.2 $response Section and Operator Specification
    • 11.15.3 Examples Including $response Section
  • 11.16 Electronic Couplings for Electron- and Energy Transfer
    • 11.16.1 Eigenstate-Based Methods
    • 11.16.2 Diabatic-State-Based Methods
  • 11.17 Population of Effectively Unpaired Electrons
  • 11.18 Molecular Junctions
• 12 Molecules in Complex Environments: Solvent Models, QM/MM and QM/EFP Features, Density Embedding
  • 12.1 Introduction
  • 12.2 Chemical Solvent Models
    • 12.2.1 Kirkwood-Onsager Model
    • 12.2.2 Polarizable Continuum Models
    • 12.2.3 PCM Job Control
    • 12.2.4 Linear-Scaling QM/MM/PCM Calculations
    • 12.2.5 Isodensity Implementation of SS(V)PE
    • 12.2.6 Composite Method for Implicit Representation of Solvent (CMIRS)
    • 12.2.7 COSMO
    • 12.2.8 SM8, SM12, and SMD Models
    • 12.2.9 Langevin Dipoles Model
    • 12.2.10 Poisson Boundary Conditions
  • 12.3 Stand-Alone QM/MM Calculations
    • 12.3.1 Available QM/MM Methods and Features
    • 12.3.2 Using the Stand-Alone QM/MM Features
    • 12.3.3 Additional Job Control Variables
    • 12.3.4 QM/MM Examples
  • 12.4 Q-CHEM/CHARMM Interface
  • 12.5 Effective Fragment Potential Method
    • 12.5.1 Theoretical Background
    • 12.5.2 Excited-State Calculations with EFP
    • 12.5.3 Extension to Macromolecules: Fragmented EFP Scheme
    • 12.5.4 Running EFP Jobs
    • 12.5.5 Library of Fragments
    • 12.5.6 Calculation of User-Defined EFP Potentials
    • 12.5.7 fEFP Input Structure
    • 12.5.8 Input keywords
    • 12.5.9 Examples
  • 12.6 Projector-Based Density Embedding
  • 12.7 Frozen-Density Embedding Theory based methods
    • 12.7.1 FDE-ADC
  • 12.8 Polarizable Embedding Model
• 13 Fragment-Based Methods
  • 13.1 Introduction
  • 13.2 Specifying Fragments in the $molecule Section
  • 13.3 FRAGMO Initial Guess for SCF Methods
  • 13.4 Locally-Projected SCF Methods
    • 13.4.1 Locally-Projected SCF Methods with Single Roothaan-Step Correction
    • 13.4.2 Roothaan-Step Corrections to the FRAGMO Initial Guess
    • 13.4.3 Automated Evaluation of the Basis-Set Superposition Error
  • 13.5 The First-Generation ALMO-EDA and Charge-Transfer Analysis (CTA)
    • 13.5.1 Energy Decomposition Analysis Based on Absolutely Localized Molecular Orbitals
    • 13.5.2 Analysis of Charge-Transfer Based on Complementary Occupied/Virtual Pairs
  • 13.6 Job Control for Locally-Projected SCF Methods
  • 13.7 The Second-Generation ALMO-EDA Method
    • 13.7.1 Generalized SCFMI Calculations and Additional Features
    • 13.7.2 Polarization Energy with a Well-defined Basis Set Limit
    • 13.7.3 Further Decomposition of the Frozen Interaction Energy
    • 13.7.4 Job Control for EDA2
    • 13.7.5 Visualization Tools in EDA2
  • 13.8 The MP2 ALMO-EDA Method
  • 13.9 The Adiabatic ALMO-EDA Method
  • 13.10 ALMO-EDA Involving Excited-State Molecules
    • 13.10.1 Theory
    • 13.10.2 Job Control
  • 13.11 The Explicit Polarization (XPol) Method
    • 13.11.1 Theory
    • 13.11.2 Supplementing XPol with Empirical Potentials
    • 13.11.3 Job Control Variables for XPol
    • 13.11.4 Examples
  • 13.12 Symmetry-Adapted Perturbation Theory (SAPT)
    • 13.12.1 Theory
    • 13.12.2 Job Control for SAPT Calculations
  • 13.13 The XPol+SAPT (XSAPT) Method
    • 13.13.1 Theory
    • 13.13.2 AO-XSAPT(KS)+aiD
  • 13.14 Energy Decomposition Analysis based on SAPT/cDFT
  • 13.15 The Many-Body Expansion Method
  • 13.16 Ab Initio Frenkel Davydov Exciton Model (AIFDEM)
    • 13.16.1 Job Control and Examples
  • 13.17 TDDFT for Molecular Interactions
  • 13.18 The ALMO-CIS and ALMO-CIS+CT Methods
• A Geometry Optimization with Q-Chem
  • A.1 Introduction
  • A.2 Theoretical Background
  • A.3 Eigenvector-Following (EF) Algorithm
  • A.4 Delocalized Internal Coordinates
  • A.5 Constrained Optimization
  • A.6 Delocalized Internal Coordinates
  • A.7 GDIIS
• B AOInts
  • B.1 Introduction
  • B.2 Historical Perspective
  • B.3 AOInts: Calculating ERIs with Q-Chem
  • B.4 Shell-Pair Data
  • B.5 Shell-Quartets and Integral Classes
  • B.6 Fundamental ERI
  • B.7 Angular Momentum Problem
  • B.8 Contraction Problem
  • B.9 Quadratic Scaling
  • B.10 Algorithm Selection
  • B.11 More Efficient Hartree–Fock Gradient and Hessian Evaluations
  • B.12 User-Controllable Variables
• C Q-Chem Quick Reference
  • C.1 Q-Chem Text Input Summary
    • C.1.1 Keyword: $molecule
    • C.1.2 Keyword: $rem
    • C.1.3 Keyword: $basis
    • C.1.4 Keyword: $comment
    • C.1.5 Keyword: $ecp
    • C.1.6 Keyword: $empirical_dispersion
    • C.1.7 Keyword: $external_charges
    • C.1.8 Keyword: $intracule
    • C.1.9 Keyword: $isotopes
    • C.1.10 Keyword: $multipole_field
    • C.1.11 Keyword: $nbo
    • C.1.12 Keyword: $occupied
    • C.1.13 Keyword: $opt
    • C.1.14 Keyword: $svp
    • C.1.15 Keyword: $svpirf
    • C.1.16 Keyword: $plots
    • C.1.17 Keyword: $localized_diabatization
    • C.1.18 Keyword: $van_der_waals
    • C.1.19 Keyword: $xc_functional
  • C.2 Geometry Optimization with General Constraints
  • C.3 $rem Variable List
    • C.3.1 General
    • C.3.2 SCF Control
    • C.3.3 DFT Options
    • C.3.4 Large Molecules
    • C.3.5 Correlated Methods
    • C.3.6 Correlated Methods Handled by CCMAN and CCMAN2
    • C.3.7 Perfect pairing, Coupled cluster valence bond, and related methods
    • C.3.8 Excited States: CIS, TDDFT, SF-XCIS and SOS-CIS(D)
    • C.3.9 Excited States: EOM-CC and CI Methods
    • C.3.10 Geometry Optimizations
    • C.3.11 Vibrational Analysis
    • C.3.12 Reaction Coordinate Following
    • C.3.13 NMR Calculations
    • C.3.14 Wave function Analysis and Molecular Properties
    • C.3.15 Symmetry
    • C.3.16 Printing Options
    • C.3.17 Resource Control
  • C.4 Alphabetical Listing of $rem Variables