$TESCAV group (optional) This group controls the tessellation procedure for the cavity surfaces in PCM computations. The default values for this group will normally be satisfactory. Use of the FIXPVA mechanism for dividing the surface of the atomic spheres into tesserae should allow for convergent PCM geometry optimizations. To converge to small OPTTOL values may require the use of internal coordinates, since the tessellation amounts to a finite grid (so the PCM energy is not strictly rotationally invariant). Cartesian geometry optimizations may require a high density of tesserae on the cavity surface: NTSALL=240 (or 960) This may require raising the maximum number of tesserae, see MXTS in $PCM. It is reasonable to just try internal coordinates first, as this should be sufficient w/o increasing the tesserae density. See also IFAST=1 in $PCMGRD. --- The first two arrays control the density of tesserae and the method to generate the tesserae. INITS = array defines the initial number of tesserae for each sphere. Only 60, 240 and 960 are allowed, but the value can be different for each sphere. (Default is INITS(1)=60,60,60,...) See NTSALL. METHOD = array defining the tessellation method for each sphere. The value can be different for each sphere. The default is 4 for all spheres, e.g. METHOD(1)=4,4,4,... See also MTHALL. = 1 GEPOL-GB, "Gauss-Bonet" tessellation. = 2 GEPOL-AS, "area scaling" tessellation. = 3 GEPOL-RT, "regular tessellation". = 4 FIXPVA, "Fixed points with variable area". FIXPVA gives smooth potential surfaces during geometry optimizations, works with $PCM options ICAV and IDISP (but not with IDP or IRP), and is the preferred tessellation method. --- The next three parameters are presets for filling the arrays INITS and METHOD with identical values. NTSALL = 60, 240 or 960 (default = 60) All values in the array INITS are set to NTSALL MTHALL = 1, 2, 3, or 4 (default = 4) All values in the array METHOD are set to MTHALL MTHAUT = 0 or 1 (default = 0) If RUNTYP=OPTIMIZE and frozen atoms are defined by IFCART, MTHAUT=1 will select METHOD=1 for frozen atoms. See also AUTFRE and NTSFRZ. note: Explicitly defining INITS and METHOD from the input deck will overrule the presets from NTSALL, MTHALL and/or MTHAUT. --- The following two parameters control GEPOL-RT AREATL = The area criterion (A*A) for GEPOL-RT. Tesserae with areas < AREATL at the boundary of intersecting spheres will be neglected. Default=0.010 A*A. Smaller AREATL cause larger number of tesserae. AREATL < 0.00010 is not recommended. BONDRY = Controls (by scaling) the distance within which tesserae are considered "close" to the boundary. Such tesserae will be recursively divided into smaller ones until their areas are < AREATL. The default (= 1.0) means the distance is the square root of the tessera area. A large BONDRY value like 1000.0 will lead to fine tessellation for the entire surface with all tessera areas < AREATL. --- The next two parameters are only relevant if MTHAUT=1 AUTFRE = Distance (A) for frozen atoms to be treated as moving atoms when MTHAUT=1. Default=2.0 A. NTSFRZ = 60, 240 OR 960, initial tessera number for frozen atoms. Default=60 ========================================================== ==========================================================

generated on 7/7/2017