<div dir="ltr">Dear CP2K team/users,<div><br></div><div>I am trying to use FIST to do GEO_OPT of a box of water molecules. I have following doubts.</div><div><br></div><div>1) How to implement coulombic subtraction in &BONDED --> Morse potential.</div><div><br></div><div>In CP2K the morse potential is in the form</div><div><br></div><div><em style="color: rgb(0, 0, 0); font-family: "Times New Roman"; font-size: medium;">K1*[(1-exp(-K2*(R-R0)))^2-1])</em><span style="color: rgb(0, 0, 0); font-family: "Times New Roman"; font-size: small;"> </span><br></div><div><span style="color: rgb(0, 0, 0); font-family: "Times New Roman"; font-size: small;"><br></span></div><div><span style="color: rgb(0, 0, 0); font-family: "Times New Roman"; font-size: small;">But I want to include coulombic subtraction and implement the below form. </span></div><div><br></div><div><em style="color: rgb(0, 0, 0); font-family: "Times New Roman"; font-size: medium;">K1*[(1-exp(-K2*(R-R0)))^2-1]) - D*Q1*Q2/R</em><br></div><div><em style="color: rgb(0, 0, 0); font-family: "Times New Roman"; font-size: medium;"><br></em></div><div><span style="color: rgb(0, 0, 0);"><font face="arial, sans-serif" style="" size="2">where Q1 and Q2 are charges of the atoms.</font></span></div><div><span style="color: rgb(0, 0, 0);"><font face="arial, sans-serif" style="" size="2"><br></font></span></div><div><span style="color: rgb(0, 0, 0);"><font face="arial, sans-serif" style="" size="2">Please let me know if it is possible. </font></span></div><div><span style="color: rgb(0, 0, 0);"><font face="arial, sans-serif" style="" size="2"><br></font></span></div><div><span style="color: rgb(0, 0, 0);"><font face="arial, sans-serif" style="" size="2">2) What will be the units of the energy for the expression in FUNCTION for below case. Will it be eV or CP2K internal  units? Do we need to adjust the FUNCTION manually to match the CP2K internal units (atomic units) ? Please let me know. </font></span></div><div><span style="color: rgb(0, 0, 0);"><font face="arial, sans-serif" style="" size="2"><br></font></span></div><div><span style="color: rgb(0, 0, 0);"><font face="arial, sans-serif" style="" size="2"> </font></span><font color="#000000" face="arial, sans-serif" size="2">        &GENPOT                                                                                                                        </font></div><div><font color="#000000" face="arial, sans-serif" size="2">          ATOMS OWAT OWAT                                                                                                              </font></div><div><font color="#000000" face="arial, sans-serif" size="2">          FUNCTION ((A/(r^12))-(B/(r^6)))                                                                                              </font></div><div><font color="#000000" face="arial, sans-serif" size="2">          PARAMETERS A B                                                                                                               </font></div><div><font color="#000000" face="arial, sans-serif" size="2">          UNITS eV*angstrom^12 eV*angstrom^6                                                                                           </font></div><div><font color="#000000" face="arial, sans-serif" size="2">          VALUES  39344.98  42.15                                                                                                      </font></div><div><font color="#000000" face="arial, sans-serif" size="2">          VARIABLES r                                                                                                                  </font></div><div><font color="#000000" face="arial, sans-serif" size="2">          RCUT [angstrom] $WATERCUTOFF                                                                                                 </font></div><div><font color="#000000" face="arial, sans-serif" size="2">        &END GENPOT     </font></div><div><font color="#000000" face="arial, sans-serif" size="2"><br></font></div><div><font color="#000000" face="arial, sans-serif" size="2">Have a nice day.</font></div><div><font color="#000000" face="arial, sans-serif" size="2"><br></font></div><div><font color="#000000" face="arial, sans-serif" size="2">Thanks and Regards,</font></div><div><font color="#000000" face="arial, sans-serif" size="2">Prasanth.                                                 </font></div></div>