import>Jss43 at 14:17, 14 December 2006

2006-12-14T14:17:11Z

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The following options for the local CPMD code are in addition to the options given in the manual for CPMD v3.11.1. Please keep any changes to this page up-to-date with the LOCAL_MODS file.

== &CPMD section ==

* QMC
Run NECI code using Kohn-Sham orbitals generated by CPMD. Need to perform a wavefunction optimization calclulation first---requires the RESTART file and the QMC input file (default filename: inp.)

* 4-INDEX INTEGRALS
Compute the integrals <math><i|v_{xc}|j></math> and <math><ij|kl></math> if not doing a QMC run. (Calculated on the fly or as an initialisation for QMC jobs.)

* RESTART SYMMETRY 2-INDEX 4-INDEX
Read in the symmetry, <math>v_{xc}</math> and 4-index integrals respectively, from the files SYMMETRY, 2INDEXINT and 4INDEXINT.

== &QMC section ==

Specify options relevant to a QMC job.

* INPUT FILE <filename>
QMC input filename.

* MEMORY ALLOCATE <Memory in MB>
Specify the size of memory block to use to store wavefunctions in real space in MB. Default is 500MB.

* INTEGRALS FAST
Compute the four-index integrals quicker using a coarser mesh (currently not working---don't use).

* INTEGRALS PRINT
Print out the 'non-special' <math><ab|cd></math> integrals to the file abcdint.

== &SYM section ==

Options for symmetry code.

* CALC SYM [ALL,OFF]
ALL: Calculate characters due to rotational symmetry for all operations rather than by classes (default). If the system is non-symmorphic, then characters are found for each operation automatically.

OFF: Turns symmetry off (by setting each state to be totally symmetric).

* INTERPOLATE <NSHELLS>
A symmetry operation may not necessarily move us from one mesh point to another. A Lagrange interpolation process is used to find the wavefunction by using NSHELLS (default 1) of boxes around the point (i.e. an interpolation of order 2*NSHELLS-1). The scaling is not so nice, but you shouldn't really need to ever go above 2 (and 1 is almost always good enough).

* INT STEP <SYMINTSTEP>
The calculation of characters by <psi|R|psi> over the real space mesh is fairly costly. Integrating using a step size of SYMINTSTEP (default 1) can speed things up significantly for large high-symmetry systems. Integrating using every other point (INT STEP 2) is a good value---there appears to be little loss in accuracy. SYMINTSTEP=4 is less good (i.e. really shouldn't be used). A check is made the the specified value is consumerate with the real space mesh (if it isn't, then SYMINTSTEP=1 is set).

* TRANS SYM OFF
Turn off translational symmetry for supercells. (Not applicable if space group symmetry is used.)

* SPACE GROUP [OFF]
Use rotational and translational symmetry (if applicable) separately, rather than all the symmetry operations of the space group.

* DEGEN TOL <DEGEN TOL>
Specify the tolerance for two states to be considered degenerate. Default is 1.d-6.

== &QMC section ==

Specify options relevant to a QMC job.

* INPUT FILE <filename>
QMC input filename.

* MEMORY ALLOCATE <Memory in MB>
Specify the size of memory block to use to store wavefunctions in real space in MB. Default is 500MB.

* INTEGRALS FAST
Compute the four-index integrals quicker using a coarser mesh (currently not working---don't use).

* INTEGRALS PRINT
Print out the ''non-special'' <math><ab|cd></math> integrals to the file abcdint.

&SYM section:
Options for symmetry code.

* CALC SYM [ALL,OFF]
ALL: Calculate characters due to rotational symmetry for all operations rather than by classes (default). If the system is non-symmorphic, then characters are found for each operation automatically.

OFF: Turns symmetry off (by setting each state to be totally symmetric).

--[[User:jss43|james]] 14:17, 14 December 2006 (GMT)

CPMDInput - Revision history

import>Jss43 at 14:17, 14 December 2006