# What is smearing in Quantum Espresso?

## What is smearing in Quantum Espresso?

1 Answer. 1. 3. Smearing is a mathematical trick implemented in codes like quantum ESPRESSO so as to aid in convergence. It has no physical meaning.

**What is Alat in Quantum Espresso?**

Atomic coordinates¶ In PWscf terms, alat = celldm(1) = lattice constant “a” in a.u. . A length in a.u. means a unit or Bohr = a0 = 0.52917720859 Angstrom. To calculate the PDOS, atomic coordinates from MD trajectories have to be in cartesian coordinates.

### What language is Quantum Espresso in?

C

Fortran

Quantum ESPRESSO/Programming languages

**Is Quantum Espresso open source?**

Quantum ESPRESSO, developed by Quantum ESPRESSO Foundation, is the leading high-performance, open-source quantum mechanical software package for nanoscale modeling of materials. Quantum ESPRESSO implements plane wave density-functional theory in conjunction with periodic boundary conditions and pseudopotentials.

#### How do you choose smearing in Quantum Espresso?

In principle, the smearing should be as small as possible and the k points mesh as large as possible. Then for degauss => zero and kpoints => infty, you should get the right value, for any quantity.

**What is electron smearing?**

Electron smearing The electrons of a system will occupy the lowest Kohn–Sham eigenstates up to a given energy level according to the Aufbau principle. One approach of doing this is to assign a finite temperature to the electron Fermi–Dirac distribution.

## How do I choose K points for Quantum Espresso?

There are three choices for the k sampling in terms of the distance between two k points.

- Very fine [0.15 1/A]
- Fine [0.2 1/A]
- Normal [0.3 1/A]

**What is VC relax?**

‘vc-relax’ and ‘relax’ are two quite different functionalities of the PW module. ‘vc’ stands for ‘variable cell’, so the cell shape (angles and length) as well as the atomic coordinates are optimized. ‘relax’ only does the atomic coordinates optimization, i.e., only the forces are calculated.

### How do I run Quantum Espresso in Linux?

1. Day 1 (installation)

- Install Quantum Espresso.
- (a) First of all, install the following basic software by typing.
- $sudo apt-get install build-essential fftw3-dev gfortran.
- (b) Then, install software to be used for graphical analysis.
- $sudo apt-get install xcrysden.
- $sudo apt-get install gnuplot.

**Who developed quantum espresso?**

Quantum ESPRESSO Foundation

Quantum ESPRESSO is a suite for first-principles electronic-structure calculations and materials modeling, distributed for free and as free software under the GNU General Public License….Quantum ESPRESSO.

Developer(s) | Quantum ESPRESSO Foundation (QEF) |
---|---|

License | GNU General Public License |

Website | quantum-espresso.org |

#### Is Quantum Espresso free?

Quantum ESPRESSO is a suite for first-principles electronic-structure calculations and materials modeling, distributed for free and as free software under the GNU General Public License.

**What is the use of Quantum Espresso?**

Quantum Espresso (QE) is an integrated suite of Open-Source computer codes for electronic-structure calculations and materials modeling. It is based on density-functional theory, plane waves, and pseudopotentials.

## When to restart a PWscf calculation from scratch?

From scratch. This is the normal way to perform a PWscf calculation ‘restart’: From previous interrupted run. Use this switch only if you want to continue an interrupted calculation, not to start a new one, or to perform non-scf calculations.

**What kind of software is PWscf used for?**

PWscf ( Plane-Wave Self-Consistent Field) is a set of programs for electronic structure calculations within density functional theory and density functional perturbation theory, using plane wave basis sets and pseudopotentials. The software is released under the GNU General Public License .

### What do you need to know about Quantum ESPRESSO?

Quantum ESPRESSO is a suite for first-principles electronic-structure calculations and materials modeling, distributed for free and as free software under the GNU General Public License. It is based on density-functional theory, plane wave basis sets, and pseudopotentials (both norm-conserving and ultrasoft).

**What kind of theory is espresso based on?**

It is based on density-functional theory, plane wave basis sets, and pseudopotentials (both norm-conserving and ultrasoft). ESPRESSO is an acronym for opEn-Source Package for Research in Electronic Structure, Simulation, and Optimization.