Back to the main page of this manual  Input reference of CP2K version 2.4.0 (Revision 12993) 
ALPHA .30  
alpha parameter associated with Ewald (EWALDPMESPME). Recommended for small systems is is alpha = 3.5 / r_cut. Tuning alpha, r_cut and gmax is needed to obtain O(N**1.5) scaling for ewald.  
This optional keyword cannot be repeated and it expects precisely one real.  
Default value: 3.50000000E01  
Default unit: [angstrom^1] 
EPSILON 1E6  
tolerance of gaussians for fft interpolation (PME only)  
This optional keyword cannot be repeated and it expects precisely one real.  
Default value: 1.00000000E06 
EWALD_ACCURACY {REAL}  
Expected accuracy in the Ewald sum. This number affects only the calculation of the cutoff for the realspace term of the ewald summation (EWALDPMESPME) as well as the construction of the neighbor lists (if the cutoff for nonbonded terms is smaller than the value employed to compute the EWALD realspace term). This keyword has no effect on the reciprocal space term (which can be tuned independently).  
This optional keyword cannot be repeated and it expects precisely one real.  
Default value: 1.00000000E06  
Default unit: [hartree] 
EWALD_TYPE {EWALDSPMEPMENONE}  
The type of ewald you want to perform. NONE standard realspace coulomb potential is computed together with the nonbonded contributions. EWALD is the standard nonfft based ewald. SPME is the smooth particle mesh using betaEuler splines (recommended). PME is the particle mesh using fft interpolation.  
This optional keyword cannot be repeated and it expects precisely one keyword.  
Default value: EWALD  
List of valid keywords:


This keyword cites the following references: [DARDEN1993] [ESSMANN1995] [Ewald1921] 
GMAX 25 25 25  
number of grid points (SPME and EWALD). If a single number is specified,the same number of points is used for all three directions on the grid.If three numbers are given, each direction can have a different number of points.The number of points needs to be FFTable (which depends on the library used) and odd for EWALD.The optimal number depends e.g. on alpha and the size of the cell. 1 point per Angstrom is common.  
This optional keyword cannot be repeated and it expects a list of integers. 
NS_MAX 11  
number of grid points on small mesh (PME only), should be odd.  
This optional keyword cannot be repeated and it expects precisely one integer.  
Default value: 11 
O_SPLINE 6  
order of the betaEuler spline (SPME only)  
This optional keyword cannot be repeated and it expects precisely one integer.  
Default value: 6 
RCUT 5.0  
Explicitly provide the realspace cutoff of the ewald summation (EWALDPMESPME). If present, overwrites the estimate of EWALD_ACCURACY and may affect the construction of the neighbor lists for nonbonded terms (in FIST), if the value specified is larger than the cutoff for nonbonded interactions.  
This optional keyword cannot be repeated and it expects precisely one real.  
Default unit: [angstrom] 
Back to the main page of this manual or the CP2K home page  (Last update: 19.6.2013) 