Quantum Mechanics: Physics

Contents

Release 4.5, June 2000

Contents

1. How to Use This Book

Who should use this book

How to find information

Other Cerius2 books

Electronic information sources

Typographical conventions

2. Quantum Physics Modules

Computational chemistry overview

Molecular mechanics methods

Quantum mechanics -- the ab initio approach

Quantum 2 application overview

CASTEP

ESOCS

FastStructure

Consistent user interface

Quantum 2 job execution and control

Interactive run mode

Background run mode

NQS run mode

Job control

SGI system patch

Bug reporting

3. General Theory

Introduction

Density functional theory

4. CASTEP

Introduction

CASTEP theory

Introduction

The finite basis set correction

Optical properties

Evaluation of the dielectric constant

Details of the computation

Limitations of the method

CASTEP methodology

Using the CASTEP user interface

Setting up a CASTEP job

Running and controlling a CASTEP job

Studying CASTEP output

CASTEP input and output datafiles

Setting up and running a CASTEP job

Preparing the molecular system for study

Defining tasks, approximation methods, and basis sets

Task

Method

Basis set

Other calculation options

Pseudopotentials

Electronic minimizer

K-points

Output and SCF options

Optical Properties

Producing optical spectra

Effects of varying the parameters

The question of accuracy and precision

The choice of properties to be output

Geometry constraints

Running the job

To set up and run a CASTEP job

Controlling CASTEP jobs

Studying CASTEP output

Accessing the tools

To retrieve and analyze model data

To analyze band structure

To analyze electronic density of states

To analyze charge density

To analyze orbitals

To analyze optical spectra

5. ESOCS

Introduction

ESOCS theory

Periodic boundary conditions and Bloch's theorem

Secular equation

Basis set used by ESOCS

The Atomic Sphere Approximation (ASA)

The k-point integrations

Quantities calculated by ESOCS

Spin orbit coupling

Optical properties calculated by ESOCS

Mixing scheme

ESOCS methodology

Introduction

Using the ESOCS user interface

ESOCS input and output files

Setting up and running an ESOCS job

Building a crystal

Defining tasks and methods

SCF options

K-points

Setting up a spin-polarized calculation

Changing the default sphere radii

Using ESOCS for open structures

Finding empty spheres positions

Changing the valence state

Running the job

Reusing potentials from a previous run

Controlling ESOCS jobs

Analyzing ESOCS results

Using the Analyze tools

Analyzing the band structure

Analyzing the density of states

Analyzing optical spectra

Analyzing magnetic moments

6. FastStructure

Introduction

Theory

Energy and force calculation via the Harris functional

Computational details

Periodic boundary conditions

The q=0 approximation

Long-range electrostatics: the Ewald method

Structure optimization and simulated annealing

Example optimizations

FastStructure methodology

Introduction

Using the FastStructure user interface

Setting up the FastStructure job

Running and controlling the FastStructure job

Study the FastStructure output

FastStructure input and output data files

Setting up and running a FastStructure job

Preparing the model system for study

Defining tasks, approximation methods and basis sets

Task

Method

Basis set

Single point energy options (multiple k-points)

Geometry optimization options

Simulated annealing options

Density/charge optimization

Output options

Geometry constraints

Atom Constraints

Transform Cell

Find Symmetry

Brillouin Zone

Running the job

To set up and run a FastStructure job

Controlling FastStructure jobs

Studying FastStructure output

Accessing the tools

To examine the FastStructure .outfs output file

To analyze energy history

To analyze forces

To analyze charges

To analyze band structure and density of states

Band structure

Density of states

Orbital basis functions in band structure calculations

The Fermi Energy

To analyze orbitals

A. References

B. Configuring CASTEP

CASTEP UI

Example CASTEP applcomm.db file entry

C. CASTEP results

Validation of pseudopotentials and of cell optimization algorithm

D. FastStructure Standalone Mode

The executable

Keywords

E. CASTEP File Formats

Parameters file (.param)

Runtime parameters file (.rundat)

F. Ultrasoft potentials testing grid