The CHSSI CCM6 Self-Consistent Atomic Deformation (SCAD) Module

The Method

Self-Consistent Atomic Deformation (SCAD) is a first-principles method of computing electronic charge densities and total energy, based on Density Functional Theory (DFT). The theory behind the method is described in this preprint (Adobe Portable Document Format reader required).

The Code

The SCAD code is a highly parallelized implementation of the SCAD method. The actual density functional evaluation part of the code is intrinsically ``Order-N (O[N])'', meaning that the computational work increases linearly with the number of atoms in the system.

Obtaining the SCAD code: Downloading the SCAD code requires registration. To register, please go to the CHSSI CCM-3 and CCM-6 Code Registration page. After registration, you will receive an email detailing the procedure for downloading the SCAD code.

• SCAD User's Manual
• We compute phonon frequencies using the total energies computed via SCAD code from supercell information determined by the FROZSL program, developed by Stokes and Boyer.
  • Directions for Using FROZSL
  • Online version of FROZSL

Lessons Learned

Section 2.1.2 of the Revised CCM6 Report to the External Reviewers describes the tests conducted on the SCAD module the CCM-6 Operational Test Readiness Review (OTRR). It serves as a useful description of the capabilities of the code. In particular, users are advised to study Table 2 of this report, which shows the performance of the SCAD code as a function of system size on various platforms.

It should be noted that performance is highly dependent upon the number of atoms in the system and the platform, and that, on a given platform, there is an optimal number of processors to be used for a given number of atoms. In particular, better parallelization is achieved if each processor handles multiple atoms, i.e., the ideal number of processors is no more than half of the number of atoms in the problem.

Publications

We have a number of publications which describe applications of the SCAD Method:

Jump to the SCAD Publication Page

Page Created: 10 May 2002	Last Update: 11 March 2003	URL: http:// cst-www.nrl.navy.mil/ccm6/ scad/index.html
Contact: mehl@dave.nrl.navy.mil	This page was produced at the Center for Computational Materials Science of the Naval Research Laboratory.

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