Most manufacturers provide free PSpice model files (.lib or .mod). In LTspice or ngspice, you can simply add the directive: .lib C:\path\to\your\model.lib
Download PSpice for TI if you want to learn the industry tool. Download LTspice if you just need the job done quickly. Have a specific circuit you are trying to simulate? Let us know in the comments below.
This allows free tools to simulate circuits that originally required a paid PSpice license. You do not need to spend $5,000 to simulate circuits professionally. PSpice for TI gives you the official Cadence interface at zero cost, while LTspice gives you unlimited freedom.